07 Heme

Cancer Treatment

When treating cancer, a cure is always the first goal. If that is not possible, then treatment can aim to slow disease progression, or it can be palliative (treats symptoms only).

Surgery can remove a well-contained tumor. If a tumor has invaded into tissue, or is surrounded by vital structures (e.g., brainstem), it can aim to reduce the size of a tumor.

If possible when removing a tumor, a surgeon typically removes a ring of healthy tissue, and aims for negative margins microscopically, meaning that there is no histologic evidence of cancer at the edges of the sample. The surgeon can send a sample to pathology and wait for the microscopic results before finishing the surgery.

Radiation therapy can decrease tumor size or kill any existing tumor cells. It can be either curative or palliative.

Radiation damages DNA, preventing the tumor cells from dividing, or directly kills the tumor cells. Adjacent structures also receive a smaller dose of radiation, leading to possible side effects, including:

• Slower wound healing

• Fibrosis of tissue, leading to strictures, ulcerations, or fistula

• Skin irritation

• Esophagitis

• Gastritis

• Pneumonitis

• Neurologic defects

• Bone marrow suppression

• Secondary cancers (e.g., sarcomas, thyroid cancer, CML - chronic myelogenous leukemia)

Chemotherapy has several possible goals. It can:

• Be first line therapy against some tumors (e.g. small cell lung cancer)

• Eradicate smaller tumors that are not good targets for surgery or radiation

• Sensitize cancer cells to radiation therapy (i.e. radiosensitizing chemotherapy)

Chemotherapy works by damaging cell DNA or preventing replication. Typically, multiple drugs that act on different parts of the cell cycle are used in order to maximize cancer cell death and minimize toxicity to normal tissue. The choice of specific chemotherapeutic agent for a specific cancer is based on clinical trials for efficacy.

Cancer-related cachexia is a hypercatabolic state characterized by loss of appetite and weight loss with a disproportionate loss of skeletal muscle.

Progesterone analogs (e.g megestrol acetate, medroxyprogesterone) and corticosteroids (e.g dexamethasone) are the first-line agents for the treatment of patients with cancer-related cachexia.

Given the multitude of adverse effects associated with corticosteroids, progesterone analogs are preferred in patients with longer life expectancies.

Chemotherapy

Methotrexate is a folic acid analog that inhibits dihydrofolate reductase. By inhibiting this enzyme, it stops DNA & protein synthesis, hindering S-phase.

Its chief toxicity is bone marrow suppression. Leucovorin (folinic acid) can be given to combat this toxicity.

Other antimetabolites include cytarabine, azathioprine, and 6-MP (6-mercaptopurine).

Dactinomycin intercalates DNA. It is used for children’s tumors including Wilms’ tumor, Ewing sarcoma and rhabdomyosarcoma.

Doxorubicin generates free radicals to intercalate DNA. Its major toxicity is dilated cardiomyopathy.

Dexrazoxane is an iron chelating agent used to prevent doxorubicin-mediated cardiotoxicity.

Bleomycin induces free radical formation & causes breaks in DNA. Its main toxicity is pulmonary fibrosis, but does not cause myelosuppression (vs. busulfan, which does).

Busulfan alkylates DNA. It can cause pulmonary fibrosis and myelosuppresion (vs. bleomycin, which also causes pulmonary fibrosis, but not myelosuppression).

Cyclophosphamide covalently links DNA at guanine N-7.

Cyclophosphamide causes hemorrhagic cystitis or bladder cancer. The cystitis is prevented with mesna.

The nitrosoureas include carmustine, lomustine, semustine and streptozocin. They can cross the blood-brain barrier and treat brain cancer.

Vinca alkaloids include vincristine and vinblastine. They function by binding to tubulin and blocking polymerization so the mitotic spindle cannot form. Contrast this with the taxols.

Vinblastine causes bone marrow suppression.

Vincristine causes neurotoxicity.

Taxols include paclitaxel and docetaxel. They bind to polymerized microtubules and stabilize the mitotic spindle so it cannot break down. Contrast this with the vinca alkaloids.

Platinum drugs including cisplatin and carboplatin cause nephrotoxicity and acoustic nerve damage. The nephrotoxicity is preventable with amifostine.

Hydroxyurea inhibits ribonucleotide reductase, decreasing DNA synthesis.

5-FU (5-fluorouracil) is an antimetabolite, that blocks thymidylate synthase, thereby blocking protein and DNA synthesis.

5-FU can cause photosensitivity and bone marrow suppression that is not relieved by leucovorin.

Acute Leukemia

ALL

Acute Lymphoblastic Leukemia (ALL) is a cancer of immature lymphoblasts. B-cells are most commonly involved, but T-cell disease is also seen.

Immature lymphoblasts clonally proliferate and replace normal bone marrow. Consequently, other blood cell lines are decreased, leading to thrombocytopenia, anemia, and neutropenia.

Children 2-5 years old are commonly affected. It is more common in boys and caucasians. ALL is the most common type of cancer & leukemia in children in the US.

Patients with Trisomy 21 are at particularly increased risk of developing ALL.

T ALL

Acute lymphoblastic leukemia (ALL) occurs when there is a neoplastic proliferation (>20%) of lymphoblasts positive for terminal deoxynucleotidyl transferase (TdT). ALL can be subcategorized into precursor B cell lymphoblastic leukemia/lymphoma (pre-B ALL) and precursor T cell lymphoblastic leukemia/lymphoma (pre-T ALL).

Lymphoblasts in both pre-B ALL and pre-T ALL exhibit some of the following characteristics:

• Positive TdT

• Positive periodic acid Schiff (PAS) staining

Precursor T cell lymphoblastic leukemia/lymphoma (pre-T ALL) usually arises in males in their teens or early twenties.

Patients with T-ALL classically present with an anterior mediastinal mass that may be associated with pleural effusions.

Though there are variations depending on subtype, lymphoblasts in pre-T ALL generally express the following unique markers on flow cytometry:

• CD3

• CD7

In contrast to B-ALL, lymphoblasts in T-ALL do not commonly express CD10 (also known as CALLA, common acute lymphoblastic leukemia antigen).

B ALL

Precursor B cell lymphoblastic leukemia/lymphoma (pre-B ALL) occurs most frequently in childhood. It is slightly more common in males, and occurs three times more frequently in whites than in blacks.

The prognosis of pre-B ALL is dependent on the cytogenetic and molecular abnormalities. Though there are several types, the most common include the following:

• In children, t(12;21) is probably the most common. It is associated with a generally favorable prognosis.

• In adults, t(9;22) (the Philadelphia chromosome) is probably the most common. It is more commonly associated with chronic myelogenous leukemia, but when it occurs in acute leukemia, it is associated with a generally poor prognosis.

Though there are variations depending on subtype, lymphoblasts in pre-B ALL generally express the following unique markers on flow cytometry:

• CD10 (common acute lymphoblastic leukemia antigen, CALLA)

• CD19

• CD20

Since CD3 is a T-cell marker, malignant lymphoblasts in pre-T ALL express CD3. In contrast, malignant lymphoblasts in pre-B ALL do not express CD3.

Treatment

Philadelphia chromosome negative ALL is treated with combination chemotherapy. Since CNS metastasis is common, prophylactic intrathecal chemotherapy with methotrexate is also used.

A tyrosine kinase inhibitor of BCR-ABL1 (e.g. imatinib, dasatinib) should be added to chemotherapy for the treatment of Philadelphia chromosome positive ALL.

AML

Acute Myelogenous Leukemia (AML) is a leukemia caused by the failure of bone marrow stem cells to mature at an early stage and subsequent suppression of all cell lines. Rapid proliferation of these immature myeloid cells results in their accumulation in the bone marrow, blood, spleen and liver.

AML is associated with a myriad of genetic translocations. The WHO classification system classifies AML based on genetic mutations, and has replaced the French-American-British system (i.e., M0, M3 classifications). Of note, a t(15;17) translocation is specific for acute promyelocytic leukemia, a subtype of AML.

AML patients are commonly elderly (median age of onset is 65 years), and female.

Auer rods are pathognomonic for myeloblasts seen in AML (acute myelogenous leukemia). They are pink, rod-like, peroxidase-positive, granular cytoplasmic inclusions.

AML patients present with symptoms of pancytopenia (anemia, neutropenia, thrombocytopenia), including infections, fatigue, pallor, bone pain, bleeding.

An AML diagnosis requires demonstrating the leukemic cells are myeloid in origin, not lymphoid. The cells can be checked for myeloperoxidase, Auer rods or other myeloid markers. Pancytopenia may also be present.

A bone marrow biopsy showing >20% blasts is also required for diagnosis.

Complications of AML frequently include anemia, infection and bleeding. More serious complications such as leukostasis, metabolic abnormalities, CNS involvement, neutropenic enterocolitis occur more rarely. When Auer rods are released during chemotherapy, DIC (disseminated intravascular coagulation) can also result.

AML is treated with chemotherapy. Certain types of AML have more specific treatments.

Acute Promyelocytic Leukemia (APL), a subtype of AML, can be treated with all-trans retinoic acid (vitamin A), which induces differentiation of myeloblasts. Chemotherapy may or may not be used additionally. However, when the Auer rods are released from the cells, DIC can result as a complication of treatment.

Appropriate supportive therapy for AML patients includes:

• Platelet transfusions, especially in acute promyelocytic (M3) leukemia to prevent DIC

• Red blood cell transfusions

• Antibiotics for febrile patients

• Uric acid lowering agents

Chronic Leukemia

CLL

CLL (Chronic Lymphocytic Leukemia) is a lymphoproliferative disorder with accumulation of functionally incompetent, but mature-appearing lymphocytes. It is virtually synonymous with SLL (Small Lymphocytic Lymphoma).

CLL is the most common leukemia in Western countries, and is more common in Caucasians, males, and the elderly (median age of onset is 70 years).

Symptoms

CLL is usually asymptomatic. Rarely, it can have painless lymph node swelling, nonspecific “B” symptoms of leukemia, or immunodeficiency symptoms. Can present with extreme fatigue. Can also presents with infections such as pneumonia.

Lymphadenopathy and hepatosplenomegaly are often physical exam findings at diagnosis.

Leukemia cutis, plum-colored purpura, is a cutaneous manifestation of leukemia.

In CLL (Chronic Lymphocytic Leukemia), the most diagnostic finding on lab work is smudge cells on peripheral smear.

Diagnosis of CLL (chronic lymphocytic leukemia) is made based on immunohistochemical staining and a peripheral smear. These tests will show:

• Prominent lymphocytosis with mild pancytopenia otherwise.

• B-Cells with classic B-Cell markers (CD19, 20, 23), as well as CD5+ (a classic T-Cell marker).

• Warm autoimmune hemolytic anemia.

• >30% lymphocytes on bone marrow biopsy.

The most common complications of CLL are immunosuppression and resultant infection, anemia and thrombocytopenia. Tumor lysis syndrome is also a concern with some therapies. Prophylactic therapies including antibiotics and transfusions should be considered.

Treatment

Early, asymptomatic CLL requires no treatment.

Localized disease can be treated with radiation.

Chemotherapy is required for advanced, symptomatic CLL. A common regimen is fludarabine, cyclophosphamide and rituximab.

Staging

There are two staging systems for CLL, the Rai and Binet staging systems. Each uses blood tests & physical exam findings to classify patients. CT scans are not routinely performed as part of staging.

The Rai system divides patients based on laboratory data and physical exam findings. Similar to the Binet system, a later stage denotes a poorer prognosis. Additionally, a higher stage implies lesser chance for achieving remission.

• Stage 0: lymphocytosis

• Stage I, II: lymphadenopathy, organomegaly

• Stage III, IV: anemia, thrombocytopenia

The Binet system looks at the number of lymph node sites involved. Similar to the Rai system, a later stage denotes a poorer prognosis.

• Stage A: Fewer than 3 lymph node sites involved

• Stage B: 3 or more lymph node sites involved

• Stage C: Presence of anemia or thrombocytopenia

CML

CML (Chronic Myelogenous Leukemia) is a myeloproliferative disorder with uncontrolled proliferation of mature and maturing granulocytes.

CML is due to a constitutively active tyrosine kinase, which is implicated in the pathogenesis of CML. A t(9;22) translocation, that forms a fusion protein, BCR-ABL1 is responsible.

The median age of onset for CML is 50 years, although typical ages range from 30 to 60 years.

• Nonspecific complaints - fever, malaise, sweating, weight loss

• Early satiety (enlarged spleen pushes on stomach)

• Left upper quadrant pain (due to spleen infarction or splenomegaly)

Physical exam shows hepatosplenomegaly due to leukocyte accumulation there.

The key laboratory finding in CML (Chronic Myelogenous Leukemia) is the presence of a Philadelphia Chromosome. It is the result of the t(9;22) translocation, leaving a shortened long arm of chromosome 22. Alternatively, the BCR-ABL1 fusion protein can be demonstrated.

The diagnosis of CML can be confirmed by karyotyping, fluorescence in situ hybridization (FISH), or reverse transcription polymerase chain reaction (RT-PCR).

• Karyotyping will show the Philadelphia chromosome

• FISH analysis can tag BCR & ABL genes, and show their juxtaposition

• RT-PCR can show the BCR-ABL fusion transcript

In contrast to leukemoid reaction (a benign leukocytosis of >50,000/mm3), CML has a low leukocyte alkaline phosphatase (LAP) score.

Absolute basophilia is almost always found on peripheral blood smear of patients with CML. Absolute eosinophilia is also commonly seen.

CML may convert to ALL or AML in a “blast crisis”, where myeloid or lymphoid blasts proliferate. Blast crisis is usually fatal.

Tyrosine kinase inhibitors (TKIs) are the drug of choice in early phase CML (Chronic Myeloid Leukemia). They function by inhibiting the constitutively active tyrosine kinase produced by bcr-abl in Philadelphia-chromosome-cells. Therefore, they stop proliferation and promote apoptosis in these leukemic cells. This drug class includes imatinib, dasatinib, and nilotinib.

Blast crisis usually does not respond to TKIs long-term, and may need hematopoietic stem cell transplant.

Hairy Cell Leukemia

Hairy cell leukemia is a relatively uncommon, clonal B-cell malignancy.

It is more common in Caucasians and males. It is a disease of middle age, with the median age of 40 years.

Hairy cell leukemia patients present with pancytopenia and hepatosplenomegaly, due to hairy cell infiltration of bone marrow, liver and spleen. The leukemic cells do not commonly infect lymph nodes. Patients can also be asymptomatic.

Due to disease infiltration of bone marrow, spleen and liver, patients complain of:

• Fatigue- from anemia

• Bleeding- from thrombocytopenia

• Infections & fever - from neutropenia

• Abdominal discomfort - from hepatosplenomegaly

Diagnosis of hairy cell leukemia is made by immunohistochemistry. Cells are positive for CD103, CD11c and CD25, along with B-cell markers (CD19, CD20, CD22). Annexin-A1 is a specific, but not sensitive finding.

It is common for a bone marrow biopsy to result in a “dry tap” due to marrow fibrosis.

On peripheral smear, hairy cells are seen. These cells are named for their small hair-like cytoplasmic projections.

Hairy cell leukemia cells also stain positive for tartrate-resistant acid phosphatase (TRAP). TRAP staining is sensitive, but not as specific as immunohistochemical staining. Flow cytometry has largely replaced TRAP staining for diagnosis.

Asymptomatic hairy cell leukemia does not need treatment. Indications for treatment include significant cytopenias, symptomatic hepatosplenomegaly, or constitutional symptoms.

The most effective initial treatment includes purine analogs, such as cladribine or pentostatin.

Splenectomy is reserved for those patients who do not respond to medical therapy, or who are bleeding from thrombocytopenia.

The prognosis in hairy cell leukemia patients is very good. Their life expectancy is nearly the same compared to individuals without HCL.

Myeloproliferative Disorders

Polycythemia Vera

Polycythemia Vera (PV) is a chronic myeloproliferative disorder characterized by increased RBC volume, and hyperviscosity syndrome.

A mutation in the JAK-2 gene causes constant stimulation of the erythropoietin-receptor in erythrocyte progenitors. All cell lines are increased, but erythrocytosis is the most drastic.

Polycythemia Vera patients will present with:

• Aquagenic pruritus (itching after a hot shower due to increased basophil release of Histamine)

• Burning pain in hands & feet (due to microvascular thrombotic events)

• Fatigue

• Easy bleeding & bruising (due to congested blood vessels)

• Headache (from hyperviscosity syndrome)

Other causes for increased hematocrit:

• Androgen abuse

Diagnosis

Making the diagnosis of polycythemia vera requires:

• Elevated hemoglobin & hematocrit

• JAK2 mutation

• Excluding other possible causes of erythrocytosis, including hypoxia, paraneoplastic syndromes, and other myelodysplastic disorders

JAK2 mutations are present in 98% of PV patients, making this the most sensitive diagnostic test.

Hemoglobin & hematocrit will be markedly elevated in PV patients. WBCs and platelets are also elevated, but erythrocytes are the most drastically increased. The cutoffs for PV are:

• Hemoglobin: >16.5 in men; and >16 in women.

• Hematocrit: >49% in men; and >48% in women.

An ABG will show oxygen saturation >92%. This is important in differentiating PV from hypoxia-induced erythrocytosis.

Erythropoietin (EPO) will be low, due to negative feedback. This excludes EPO-secreting tumors from the differential diagnosis.

The Philadelphia chromosome (9:22 translocation) will not be present, in opposition to CML (Chronic Myelocytic Leukemia), another myelodysplastic disorder.

Bone marrow biopsy will show generalized hypercellularity.

Hepatosplenomegaly will be present due to congestion & hyperviscosity syndrome.

Imaging can be used to look for tumors that produce erythropoietin. These tumors are causes of secondary erythrocytosis, not PV. The presence of these tumors rules out PV. Common tumors include:

• Pheochromocytoma

• Renal cell carcinoma

• Hemangioblastoma

• Hepatocellular carcinoma

Complications

Complications of polycythemia vera are related to hyperviscosity syndrome. PV patients are at risk for

• Myocardial infarction

• Ischemic stroke

• Budd-Chiari syndrome - an occlusion of the IVC, leading to centrilobular hepatic congestion, necrosis, and eventual liver failure.

Additionally, PV patients are at risk of developing post-PV myelofibrosis, AML (acute myeloid leukemia), or other myelodysplastic syndromes.

Treatment

The treatment of polycythemia vera consists of:

• Therapeutic phlebotomy to control hematocrit levels

• Myelosuppressive agents (e.g. hydroxyurea) for bone marrow suppression & further control of hematocrit

• Aspirin for thrombosis & erythromelalgia

• Antihistamines for pruritus

• Uric-acid lowering agents (e.g. allopurinol, rasburicase)

Treated PV patients have a life expectancy of 10 or more years. Untreated, the prognosis is poor, with a lifespan of 6-18 months.

The most common causes of death in PV are:

• Thrombosis

• Hematologic and nonhematologic malignancies

• Hemorrhage (from engorged blood vessels)

• Post-PV myelofibrosis

Lymphoma

Hodgkin

Hodgkin lymphoma originates from B-Cells.

Hodgkin lymphoma, by definition, has Reed-Sternberg (RS) cells. RS cells are large cells with owl-eyed nucleoli with a clear halo and abundant cytoplasm. They are positive for CD15 & CD30.

Hodgkin lymphoma is diagnosed based on lymph node biopsy, which shows Reed-Sternberg cells in an inflammatory background. Also has normal blood count and peripheral smear.

Most patients present with painless cervical lymphadenopathy. They also can have nonspecific “B-type” symptoms including fever, night sweats and weight loss.

Hodgkin lymphoma has a bimodal age distribution; it is more common in the young ( ~20 years old) and in the elderly ( ~65 years old). It is also associated with Epstein-Barr Virus (EBV), and a positive family history of the disease.

There are four types of Hodgkin lymphoma, diagnosed based on their histologic lymph node appearance. In order of worsening prognosis and increasing RS cells, they are:

• Lymphocyte predominance

• Nodular sclerosis

• Mixed cellularity

• Lymphocyte depleted

Prognosis is dependent on the presence of B-type symptoms as well as staging. Staging is based on disease spread and is determined by PET/CT scans.

• Stage I: Disease in a single lymph node or one other site

• Stage II: Disease in 2 or more lymph nodes or contiguous sites on the same side of the diaphragm

• Stage III: Disease in lymph nodes on both sides of the diaphragm

• Stage IV: Disease outside of lymph nodes

Early stage Hodgkin lymphoma (Stage I/II) is often cured with treatment.

In late stage (Stage III/IV), prognosis is determined by the International Prognostic Score (IPS).

All types of Hodgkin lymphoma are treated with chemotherapy. Early-stage disease is also treated with radiation.

Non-Hodgkin Lymphoma

Non-Hodgkin lymphomas present with rapidly enlarging lymphadenopathy. Disseminated disease is common at presentation, involving spleen, liver, GI tract, breast and pleura. Laboratory studies are usually normal.

While less common, abnormal laboratory values are possible and include the following:

• Anemia, thrombocytopenia, and/or leukopenia (due to bone marrow infiltration)

• Hypercalcemia (15% development at some point)

• Hyperuricemia (presents as gout or nephrolithiasis, more commonly after initial treatment)

• Elevated serum lactate dehydrogenase (LDH)

• M-spike on serum protein electrophoresis

Follicular

Follicular lymphoma is most commonly caused by an overexpression of BCL2, an important anti-apoptotic oncogene involved in B cell maturation.

A t(14;18) translocation brings bcl-2 closer to the heavy chain immunoglobulin gene in B-Cells. Other genetic lesions or host factors are also required, and t(14:18) translocations are only seen in 85% of follicular lymphoma.

Histologically, it has a nodular growth pattern that resembles germinal centers, but lacks normal germinal center architecture.

It is common in caucasians aged 60-65 and in the immunocompromised.

Burkitt

Burkitt’s lymphoma is caused by a translocation of chromosome 8, typically t(8;14), t(2;8), or t(8;22). C-myc amplification causes uncontrolled cell progression in affected B-Cells.

Histologically, lymph nodes have a “starry sky” appearance. The stars are macrophages cleaning up cellular debris from a high tumor cell turnover rate. The sky is a background of tumor cells.

Burkitt’s lymphoma tumor cells express IgM, CD10, HLA-DR, and CD43, as well as B cell-associated antigens (CD19, CD20, CD22).

It is more common in younger males, and can be associated with Epstein-Barr Virus.

Burkitt’s lymphoma has three types:

• Endemic (common in Africa), which also has jaw tumors

• Sporadic (common in the US and Western Europe), which also has abdominal distention

• Immunodeficiency-related

Mantle cell

Mantle cell lymphoma is caused by a t(11;14) translocation, linking bcl-1 to immunoglobulin heavy chain in B-Cells. Bcl-1 is over-expressed. Bcl-1, also known as Cyclin-D1, aids cell cycle G1/S transition. (Mnemonic: man11_e cell lymphoma has a chromosome _11 translocation).

Histologically, the lymph node’s mantle zone is expanded, with surrounding germinal centers.

Tumor cells characteristically are positive for bcl-1/cyclin-d1. They also have CD5, and typical B-cell markers (CD19, CD20, IgM, IgD).

Patients are typically around 60 years old, and men are affected more commonly than women.

Diffuse Large B

Diffuse, Large B-Cell Lymphoma (DLBCL) is the most common non-Hodgkin’s lymphoma, making up about 25% of cases.

Histologically, the lymph node architecture is completely effaced and replaced by atypical lymphoid cells. These cells are large and resemble immature B-Cells.

Cells will express mature B-Cell markers, such as CD19, CD20, CD22, CD79a.

Adult T Cell Lymphoma

Adult T-Cell Lymphoma (ATL) is a peripheral T-cell neoplasm caused by HTLV-1 (Human T-Lymphotropic Virus, type 1). The exact pathophysiology is poorly understood.

A peripheral smear will show flower cells, or clover-leaf cells, which have hyperlobulated nuclei. Lymph nodes show architectural effacement.

Cancer cells express T-helper cell surface markers, such as CD2, CD4, CD5. Notably, they lack CD8.

In addition to lymphadenopathy and hepatosplenomegaly which are common to many lymphomas, Adult T-Cell lymphoma can present with:

• Immunosuppression

• Hypercalcemia

• Lytic bone lesions

• Skin lesions (distinguishing it from multiple myeloma)

Non-Hodgkin’s lymphomas are treated with chemotherapy. Radiation can be used for localized cancer, but many patients present with disseminated disease.

Multiple Myeloma

Multiple myeloma is a plasma cell neoplasm of the bone marrow. It produces a large amount of monoclonal immunoglobulin (usually IgG), which causes symptoms.

Multiple myeloma occurs most frequently in older adults. Both genders are affected equally.

Principal presenting symptoms of multiple myeloma are:

• Bone pain and fractures due to lytic bone lesions

• Symptoms of renal insufficiency

• Symptoms of hypercalcemia - bones, stones, moans and groans

• Weight loss

Diagnosis

The diagnosis of multiple myeloma is made by a bone marrow biopsy showing ≥10% clonal plasma cells, and either:

• End organ damage: hypercalcemia, renal failure, anemia, bone lesions, proteinuria, immunosuppression

• Focal biomarkers of malignancy (the specifics are low-yield for USMLE)

Patients typically have Bence-Jones proteinuria or waxy, laminated casts, depending on the specific etiology of renal damage. However, urine dipstick is negative for protein, since there is little albumin in the urine. U/A often bland (urine dipstick protein typically detects albumin, not immunoglobulins) that may show evidence of granular casts. The monoclonal protein can also damage the glomeruli (amyloidosis, monoclonal immunoglobulin deposition disease), leading to nephrotic syndrome.

Histologically, numerous myeloma cells are present on bone marrow biopsy, which are plasma cells in various stages of maturation. They will have acidophilic cytoplasmic inclusions of immunoglobulin called Russell bodies.

On peripheral smear, a Rouleaux formation is often seen, which is RBC stacking.

Multiple myeloma should be distinguished from:

• Monoclonal Gammopathy of Undetermined Significance (MGUS), which does not have the end-organ damage associated with multiple myeloma and has less than 10% plasma cells on bone marrow biopsy. The risk of MGUS progressing to multiple myeloma is 1% a year.

• Waldenström macroglobulinemia (IgM myeloma), which has no end organ damage. Patients can develop symptoms of hematopoietic organs (e.g., anemia, hepatosplenomegaly, lymphadenopathy), or can be asymptomatic.

End-organ damage should be assessed in multiple myeloma patients. Evidence of complications can be remembered with the mnemonic CRABBI.

• Calcium elevation

• Renal insufficiency

• Anemia

• Bone fractures, pain and lytic lesions

• Bence Jones proteinuria

• Immunosuppression

Treatment

Multiple myeloma is incurable, even with a transplant. However, patients may be treated with:

• Hematologic stem cell transplant, if eligible

• Chemotherapy

• Activity should be encouraged to increase bone density

• Vaccines against streptococcus pneumoniae, and annual flu and haemophilus influenzae B are encouraged, given their immunosuppression

• Radiation therapy for

  • Plasmacytomas

  • Bony lesions that cause pain or compress the spinal cord

Bortezomib, carfilzomib, and ixazomib are proteasomal inhibitors that are used in the treatment of multiple myeloma. These agents inhibit chymotrypsin-like activity of proteasomal subunits, ultimately leading to cell-cycle arrest and apoptosis of myeloma cells.

Bortezomib can cause peripheral neuropathy.

Microcytic Anemia

Iron Deficiency

Iron deficiency can occur due to absolute iron deficiency or functional iron deficiency.

Absolute iron deficiency refers to decreased iron levels in body stores, typically resulting from:

• Poor nutrition

• Impaired absorption

• Blood loss

Functional iron deficiency refers to conditions in which there is insufficient availability of iron to incorporate into erythroid precursors. For example:

• Anemia of Chronic Disease - hepcidin-induced block on iron release from stores, resulting in reduced availability of iron for erythropoiesis

• Treatment with erythropoiesis-stimulating agents

Most common etiology of iron deficiency anemia in the developed world is chronic blood loss:

• Menorrhagia

• Gastrointestinal bleeding (e.g. colonic polyp or cancer)

• Meckel's diverticulum in a child

Because iron is absorbed in the duodenum, any disease process of the small bowel (e.g. Crohn's) that affects the duodenum may compromise iron absorption.

Clinical presentation of iron-deficiency anemia includes the following features:

• Pallor

• Fatigue

• Exertional dyspnea

• Spoon Nails (Koilonychia)

• Pica for ice (Pagophagia)

Plummer-Vinson Syndrome: Triad of anemia, glossitis and esophageal webs. Be suspicious if a patient presents with symptoms of dysphagia and has concurrent anemia.

Iron deficiency anemia diagnosis is based on microcytic anemia & iron studies:

• Decreased serum iron

• Decreased ferritin

• Increased TIBC (Total Iron Binding Capacity)

Serum ferritin is an acute phase reactant and can be elevated for a myriad of reasons. Therefore, it is not a reliable way to check a patient's iron status.

Iron deficiency anemia is treated by replenishing iron stores. A trial of oral iron should be given to menstruating women, but men and post-menopausal women with iron deficiency should be worked up for source of blood loss.

Oral iron is the mainstay therapy for iron deficiency anemia.

• Oral iron tablets should not be taken with tea, coffee or calcium supplements as these will decrease the absorption

• Conversely, acidity (vitamin C or orange juice) will increase the absorption of iron

Parenteral iron is used in patients who are unable to absorb iron enterally (small bowel resection, inflammatory bowel disease, etc.)

• It must be administered in the hospital.

• Generally well tolerated, however one formulation, iron dextran, can cause life-threatening anaphylaxis.

Blood products are generally reserved for patients who are unstable (either hypotensive due to bleeding or hypoxic due to anemia).

• The threshold for transfusion varies based on the patient’s co-morbid conditions and institution, but is generally considered to be hemoglobin of 7 for most patients.

Anemia of Chronic Disease

Anemia of chronic disease occurs in the setting of a chronic infectious or inflammatory process. It is one of the most common causes of anemia in hospitalized patients.

Pathophysiology of anemia of chronic disease is related to the persistent release of inflammatory mediators. Inflammatory states induce IL-6 production. IL-6 up-regulates the synthesis of hepcidin, which decreases release of iron from iron stores.

Hepcidin is a hepatic protein which inhibits transport of iron from bone marrow macrophages to developing erythrocytes, among other inflammatory functions.

Thus, erythrocyte production takes place in a state of perceived iron deficiency (despite the fact that iron stores are in fact adequate).

In anemia of chronic disease, one would expect to see the following results on iron studies:

• Low serum iron

• Low serum transferrin, or total iron binding capacity

• Low or normal transferrin saturation

• Normal or elevated serum ferritin

Sometimes, ancillary laboratory findings can assist in making the diagnosis of anemia of chronic disease:

• The reticulocyte index should be low (reflecting decreased RBC production)

• ESR/CRP can sometimes be elevated (reflecting an overall inflammatory state). ESR is the erythrocyte sedimentation rate. CRP is the C-reactive protein.

Treatment of anemia of chronic disease is to address the underlying disease.

For symptomatic anemia of chronic disease that persists despite treatment of the underlying condition, an erythropoiesis-stimulating agent can be used (e.g. EPO) in some situations.

Iron should not be used as monotherapy for anemia of chronic disease.

Sideroblastic Anemia

Sideroblastic anemia is caused by defective heme synthesis due to a variety of genetic lesions, alcohol, isoniazid or lead poisoning. The iron levels are managed symptomatically by transfusions, chelation or phlebotomy. Supplemental erythropoietin can help in acquired cases.

Some causes of sideroblastic anemia are fully reversible with removal of the offending agent. For example,

• Lead, zinc or alcohol toxicity

• Copper deficiency

• Isoniazid

• Chloramphenicol

• Hypothermia

Sideroblastic anemia can be a myelodysplastic syndrome. These patients have acquired disease (i.e. not genetic), and is not due to a reversible cause noted above. These patients may progress to an acute leukemia, and need to be monitored.

Vitamin B6 (pyridoxine)is a cofactor in the production of heme (5-Aminolevulinate synthase / ALA-Synthase). Therefore vitamin B6 can treat sideroblastic anemia.

Lead Poisoning

Lead is a heavy metal that can be absorbed by inhalation or ingestion. Paint chips can be ingested, or dust can be inhaled.

Children more commonly get lead poisoning, and the major source of exposure is lead paint. In adults, occupational exposure is more common.

Acute lead poisoning presents with abdominal and neurological symptoms. Anorexia, nausea, vomiting, headaches, ataxia, irritability, insomnia or seizures can be seen.

Chronic lead toxicity in children commonly presents with nonspecific gastrointestinal, behavioral, and peripheral neurological symptoms.

• GI: Anorexia, nausea, vomiting, constipation, abdominal pain

• Behavioral: inattentiveness, distractibility, irritability, developmental delays

• Peripheral neuropathies: weakness, peripheral palsies

Lead lines are bluish lines tracing the gingival tooth border. They appear in adults with poor dentition. Lead lines can also refer to the dense metaphyseal opacities on x-ray (see below), usually seen in children.

Peripheral neuropathy classically presents as wrist or foot drop.

Symptoms can mirror iron-deficiency anemia, because heme synthesis is blocked in both pathways.

Chronic lead poisoning can lead to hyperuricemia and gout due to impaired purine metabolism and decreased renal excretion of uric acid. Gout that is caused by lead toxicity is referred to as “saturnine gout.”

Note: Saturnine gout gets its name from the storage and drinking of wine from lead-lined containers at the festival of the Roman God Saturn. A similar phenomenon is seen with the illicit distillation of alcohol (moonshine) in containers that contain lead.

Small lead exposure may present with minor or nonspecific symptoms. However, potential long-term complications include:

• Nephropathy

• Psychiatric conditions

• Cardiac conduction delays

• Hypertension

• Hearing loss

• Gout

Since lead crosses the placenta, it is associated with miscarriages, stillbirths, low birth weight and cognitive impairments.

Diagnosis

Blood lead level is the most accurate diagnostic test, and indicates lead exposure over the last several weeks. Fingerstick test kits are available as screening tests, and collection is simpler than venous blood draws.

Bone lead levels are more indicative of total lifetime lead exposure. X-ray fluorescence (XRF) is a relatively new test for bone lead levels.

Peripheral smear shows basophilic stippling and microcytic, sideroblastic, hypochromic anemia. The anemia results from inhibition of two enzymes involved in heme synthesis: δ-aminolevulinic acid dehydratase (ALAD), and ferrochelatase.

While symptomatic children should be tested, the USPSTF (US Preventive Services Task Force) recommends against routinely screening asymptomatic children.

Treatment

Moderate or severe lead poisoning is treated with pharmacologic chelation. Mild lead levels (i.e., <45mcg/dL) are followed closely, but not treated with chelation.

• Moderate lead levels (45-69mcg/dL) are treated with DMSA or succimer for chelation.

• Severe lead poisoning (>70mcg/dL) is treated with dimercaprol or EDTA for chelation.

Thalassemia

The thalassemias are a group of hemoglobinopathies related to defective, reduced, or absent production of one or more of the globin chains.

Mutations in promoters, introns, and exons can all contribute to the development of thalassemia. Mild disease can be due to splicing defects. Severe disease can be due to missense mutations (e.g. absent β chains as is seen in β-thalassemia major).

Normal hemoglobin is called Hemoglobin A (HbA), which is one pair of alpha-globin chains and one pair of beta-globin chains.

There is a variant of normal hemoglobin, called Hemoglobin A2 (HbA2), consisting of one pair of alpha-globin chains and one pair of delta-globin chains. The delta-globin chains take the place of beta-globin chains when there is impaired synthesis (as occurs with the beta-thalassemias).

B major

β-thalassemia major occurs due to impaired production of beta-globin chains, leading to an excess of alpha-globin chains.

Infants with beta-thalassemia major generally develop symptoms after 6 months of age, when fetal hemoglobin (HbF, 2a:2y) disappears and beta-chains become necessary to form HbA.

The clinical manifestations of beta-thalassemia major are heterogeneous, but in its severest form may be characterized by:

• Skeletal changes: "chipmunk facies" and "hair-on-end" radiographic appearance of the skull, which reflect expanded peripheral hematopoiesis

• Hepatomegaly: due to increased red cell destruction

• Gallstones: due to red cell hemolysis

• Splenomegaly: due to increased red cell destruction, and extramedullary hematopoiesis

• Cardiac abnormalities, including heart failure and arrhythmias

• Aplastic crises with parvovirus B19 infections

• Severe microcytic, hypochromic anemia

• Findings of hemolytic anemia (increased indirect bilirubin, elevated LDH, decreased/absent haptoglobin)

• Hemoglobin electrophoresis confirms the diagnosis with absent or severely reduced HbA; only HbA2 and HbF are present

Patients with beta thalassemia major will die if they are not treated. Management consists of:

• Hypertransfusion protocol along with iron chelation therapy to reduce native erythropoiesis

• If clinically appropriate, hematopoietic stem cell transplant can be curative

• Additional management can include splenectomy (for some patients) and vitamin supplementation (folate, zinc, vitamin C)

B Minor

β-thalassemia Minor is characterized by mild decrease in beta-globin chain production. Because this is a mild disorder, patients are usually asymptomatic.

β-thalassemia Minor can be detected on laboratory analysis, which will reveal:

• Profound microcytosis (MCV < 75), though anemia is typically only mild if present at all

• Peripheral blood smear will demonstrate microcytes and many target cells

• On hemoglobin electrophoresis, there will be over 90% HbA with relatively increased levels of HbA2 and HbF

A thalassemia

The α-thalassemias are a group of disorders that occur due to defective alpha-globin production and resultant excess of beta-globin chains.

Normal individuals have four functional alpha-globin genes, and distinct clinical disorders result from deletion of one, two, three, or all four of these genes:

• alpha-thalassemia minima: loss of one alpha gene (not clinically significant)

• alpha-thalassemia minor: loss of two alpha genes (like beta-thalassemia minor, not clinically significant, though patients may have microcytosis and target cells; can be distinguished based on absence of HbA2 elevation on Hb electrophoresis)

• HbH disease: loss of three alpha genes

• Hydrops fetalis with Hb Barts: loss of all four alpha genes

HbH disease is characterized by presence of HbH (4 beta-globin chains), which occurs due to the absence/mutation of 3 alpha genes:

• Clinical features: hemolytic anemia at birth with neonatal jaundice and anemia; physical stigmata not as common as with beta-thalassemia major

• Diagnosis: Presence of HbH (5-30%) on Hb electrophoresis

• Management: May require transfusions and splenectomy later in life

Hemoglobin Barts disease with hydrops fetalis is characterized by the presence of hemoglobin Barts (4 gamma-globin chains), and is incompatible with extra-uterine life.

Normocytic Anemia

Aplastic Anemia

Aplastic anemia is characterized by diminished or absent hematopoietic precursors in the bone marrow.

Aplastic anemia occurs most commonly due to injury of the pluripotent stem cell, though in rare cases it can be hereditary.

Fanconi anemia is a hereditary cause of stem cell failure.

• Multiple defective genes are responsible for the disorder, ultimately resulting in impaired DNA repair mechanisms

Stem cell failure can be acquired due to exposure to certain drugs or toxin:

• Radiation

• Anti-epileptics (e.g. carbamazepine, phenytoin, valproate)

• NSAIDs

• Sulfonamides

• Chloramphenicol

• Gold

• Nifedipine

• Benzene

Stem cell failure can also be due to viral infection:

• Parvovirus B19

• Hepatitis viruses

• HIV

• Epstein-Barr virus

Aplastic anemia should be suspected in any patient with pancytopenia (i.e. anemia, leukopenia, and thrombocytopenia)

Other features of clinical presentation are due to underlying blood dyscrasias:

• Anemia → fatigue, cardiopulmonary compromise

• Leukopenia → recurrent infections, particularly with opportunistic pathogens

• Thrombocytopenia → mucosal hemorrhage

Diagnosis

The diagnosis of aplastic anemia is suggested by a CBC demonstrating pancytopenia and a decreased reticulocyte index.

Bone marrow biopsy is the key to definitive diagnosis, with the following hallmark findings:

• Profound hypocellularity with the marrow space filled mostly by fat cells and stroma

• There should be no fibrotic infiltration or malignant cells (which would be suggestive of alternative diagnoses)

• Residual hematopietic cells are morphologically normal

Treatment

Treatment of aplastic anemia depends on the underlying cause. Curing any reversible cause is the most important objective. Supportive care, such as transfusions or antibiotic prophylaxis may be appropriate.

Hemolytic Anemia

Hemolytic anemia is characterized by shortened survival time of circulating erythrocytes. In patients with hemolytic anemia, the survival time of peripheral erythrocytes is less than 100 days. This is in contrast to a lifespan of around 120 days for erythrocytes in healthy individuals.

Hemolytic anemia can be categorized based on:

• Cause (intracorpuscular vs. extracorpuscular)

• Site (intravascular vs. extravascular)

Intracorpuscular defects involve components of the RBC itself:

• Hemoglobin (e.g. alpha or beta-thalassemia)

• Cell membrane (e.g. hereditary spherocytosis)

• Metabolic machinery, such as energy producing enzymes and anti-oxidants (e.g. G6PD deficiency)

Extracorpuscular defects involve mechanical or biological factors external to the RBC:

• Antibodies directed to the erythrocyte (e.g. autoimmune hemolytic anemia)

• Hypersplenism (stasis/trapping/destruction of erythrocytes in an enlarged spleen)

• Mechanical destruction of erythrocytes (e.g. malfunctioning prosthetic heart valve, DIC, and TTP)

• Pathogen mediated destruction (e.g. Babesiosis or malaria)

• Toxins (e.g. snake venom or copper poisoning)

Intravascular hemolysis occurs when severe damage of the RBC membrane results in immediate lysis within the circulation. For example:

• Mechanical stress from defective heart valves

• Complement-mediated damage, as in paroxysmal nocturnal hemoglobinuria

• Osmotic lysis following introduction of hypotonic solution

• Toxin exposure (such as bacterial toxins or copper poisoning)

Extravascular hemolysis occurs when damaged RBCs (often coated with complement) are recognized and phagocytosed by macrophages in the liver and spleen.

While there are no signs/symptoms specific to hemolytic anemia, certain clinical features may raise suspicion:

• Rapid onset of pallor and anemia

• Presence of pigmented gallstones

• Jaundice

Diagnosis

The initial diagnostic approach involves ordering the following laboratory studies:

• CBC (complete blood count)

• Peripheral blood smear

• Reticulocyte count

• Lactate dehydrogenase (LDH) and haptoglobin

• LFTs (liver function tests)

Further investigation may require additional tests:

• Autoimmune studies (i.e. Coombs testing)

• Serum and urine free hemoglobin, and urinary hemosiderin

CBC should reveal an anemia that is typically normocytic.

Peripheral blood smear can have variable findings based on the underlying etiology:

• Spherocytes (hereditary spherocytosis or autoimmune hemolytic anemia)

• Elliptocytes (hereditary elliptocytosis)

• Schistocytes (TTP/HUS, DIC, or mechanical destruction due to prosthetic heart valve)

• Bite cells (G6PD)

The reticulocyte count (or, if available, the reticulocyte index) should be elevated to reflect a compensatory increase in RBC production.

• Typically, reticulocytes should account for >4-5% of cell count to reflect an appropriate response

Serum LDH is elevated (released from hemolyzed cells) and haptoglobin is decreased (due to consumption in the free hemoglobin-binding process)

• A finding of elevated LDH and decreased haptoglobin is around 90% specific for hemolytic anemia

• Normal LDH and normal haptoglobin are around 90% sensitive for ruling out hemolytic anemia

Indirect bilirubin is elevated due to increased RBC turnover.

Findings unique to intravascular hemolysis:

• Elevated plasma free hemoglobin

• Elevated urine free hemoglobin

• Presence of urinary hemosiderin (reflecting longer-term hemolysis)

Warm AIHA

Key Example 1: Warm autoimmune hemolytic anemia

• Characterized by IgG (warm agglutinins) that bind directly to antigens on RBC surface

Etiology is often unknown, but may be associated with several disorders:

• Preceding viral infection

• Autoimmune disorders (e.g. SLE)

• Lymphoproliferative disorders (e.g. CLL)

• Immune deficiency syndromes (e.g. common variable immune deficiency)

• methyldopa

• penicillin

Commonly results in extravascular hemolysis by splenic macrophages → splenomegaly

Management involves correcting critical hemoglobin levels with red cell transfusion, and addressing the underlying condition:

• Initial treatment – glucocorticoids

• Severe or resistant disease – splenectomy

• For those unwilling to undergo splenectomy or remain symptomatic following splenectomy – cytotoxic agents

Cold AIHA

Key Example 2: Cold agglutinin disease

• Characterized typically by the presence of IgM (anti-I) antibodies directed against RBC surfaces

Etiologies can be viral (EBV) or non-viral (Mycoplasma pneumoniae infections or lymphoproliferative disorders)

Treatment is mainly supportive:

• Cold avoidance

• In severely symptomatic patients – cytotoxic therapy, plasmapheresis

• Steroids and splenectomy are typically not effective (in contrast to management for warm hemolytic anemia)

Drug Induced

Key Example 3: Drug-induced hemolytic anemia (several distinct mechanisms) Drugs commonly implicated in hemolytic anemia include:

• Penicillins cause a hapten reaction, in which IgG recognizes the RBC Ag:Penicillin complex

• Cephalosporins cause an immune complex type of reaction, in which IgG:ceftriaxone complex is deposited on an RBC, which is subsequently destroyed due to its association with an immune complex

• Methyldopa alters Rh antigen on RBC —> IgG recognizes altered Ag

• NSAIDs - autoimmune effect similar to methyldopa

• Quinine/Quinidine - membrane disruption

Mechanical

Key Example 4: Fragmentation hemolysis, characterized by mechanical destruction of RBCs as they move through the circulation. Etiologies include:

• Prosthetic heart valves and assist devices

• DIC

• TTP

• HUS

• HELLP Syndrome

• Malignant hypertension

Diagnosis can be suggested by the following:

• Findings typical of hemolytic anemia with an intravascular pattern of hemolysis (i.e. elevated plasma and urine free hemoglobin)

• Schistocytes on peripheral blood smear

Additional Examples:

• G6PD Deficiency

• PK Deficiency

• Hereditary Spherocytosis

• Hereditary Elliptocytosis

Hereditary Elliptocytosis

Hereditary elliptocytosis is a rare autosomal dominant disorder caused by a mutation in erythrocyte membrane proteins

Common mutations occur in:

• Alpha spectrin (most common; 65% of cases)

• Beta spectrin

• Protein 4.1

• Band 3

• Glycophorin C

Similarly, hereditary spherocytosis is caused by mutations in spectrin & ankyrin.

Hereditary elliptocytosis has a higher prevalence in Africa. The disease, even a silent carrier mutation, may provide some protection against malaria, specifically P. falciparum.

There are several types of hereditary elliptocytosis. The associated hemolytic anemia ranges in severity from clinically silent to life-threatening. Severe hemolysis is due to being homozygous for the disease, or compound heterozygosity along with another structural membrane protein disorder.

Common symptoms of chronic hemolysis include:

• Splenomegaly

• Pigmented gallstones

• Leg ulcers

• Frontal bossing

• Elevated reticulocyte percentage

Similarly, the hereditary spherocytosis presents with symptoms due to hemolysis.

Common hereditary elliptocytosis is usually asymptomatic, but can be more severe. Diagnosis is made after routine blood work showing elliptocytes. Mild, lifelong hemolysis can be present.

Hereditary pyropoikilocytosis is the most severe type of hereditary elliptocytosis. Erythrocytes are especially susceptible to heat, budding and fragmentation.

Certain physiological states can worsen the hemolysis in hereditary elliptocytosis. For example,

• Neonatal period- high levels of 2,3-BPG destabilize the few remaining normal structural proteins, causing increased elliptocytosis and poikilocytes, and increased hemolysis

• Renal allograft rejection

• TTP/HUS (Thrombotic Thrombocytopenic Purpura-Hemolytic Uremic Syndrome)

• B12 deficiency

• Pregnancy

• Infection with viruses, bacteria or protozoa

Usually, no treatment is necessary for hereditary elliptocytosis. Folic Acid may help prevent deficiency in hemolytic cases. Contrast this with hereditary spherocytosis, where a splenectomy is the treatment of choice.

Only in severe cases, Splenectomy can prevent hemolysis in hereditary elliptocytosis. A blood transfusion may also be necessary.

Hereditary Spherocytosis

Hereditary Spherocytosis is a defect in the genes encoding structural red blood cell (RBC) proteins leading to the creation of red blood cells that are sphere shaped. It is usually autosomal dominant, but can also be autosomal recessive. AD

Defective proteins implicated in this disease often include those such as spectrin and ankyrin.

The defect is due to a loss of RBC membrane surface area without a decrease in RBC volume, which imposes a spherical shape on affected cells. This causes affected spherical cells to get stuck in the narrow passages of the splenic cords leading to their destruction in the spleen (hence extravascular hemolysis).

Hereditary spherocytosis can present with hemolytic anemia, jaundice, and splenomegaly.

• Hemolytic anemia can cause splenomegaly & gallstone formation (especially as patients age). The presenting hemolytic anemia can range from mild-severe depending upon the patient.

• Jaundice is usually most intense in the neonatal period as most cases are detected soon after birth.

Diagnosis

Hereditary spherocytosis is diagnosed with a variety of laboratory findings. Notably, a peripheral blood smear will show spherocytes (small cells that have lost their central pallor).

The mean corpuscular hemoglobin concentration (MCHC) will be elevated reflecting the membrane loss and red cell dehydration.

In hereditary spherocytosis, the osmotic fragility test has been replaced with eosin-5-maleimide binding test as a screening test. For confirmation, use acidified glycerol lysis test. Genetic testing for the exact mutation does not affect treatment and is not commonly performed. Coombs will be negative as opposed to autoimmune hemolytic anemia.

Complications experienced by patients with hereditary spherocytosis include:

• Hemolytic crises

• Leg ulcers

• Priapism

• Hypertrophic cardiomyopathy

Treatment of choice for hereditary spherocytosis is splenectomy. Splenectomy can eliminate or at least minimize anemia in patients with spherocytosis. The bilirubin and reticulocytosis should also fall to normal levels post procedure.

However, splenectomy is not without consequences, and should be reserved for severe disease. Remember to vaccinate against encapsulated organisms in asplenic patients: Haemophilus Influenzae, Neisseria Meningitidis,_and _Streptococcus Pneumoniae.

Supportive care can consist of folic acid, blood transfusions (especially in infants), and administration of erythropoietin.

PNH

Paroxysmal nocturnal hemoglobinuria (PNH) is a genetic defect in CD55 or CD59, or their anchoring protein, GPI. CD55 and CD59 both function to prevent complement-mediated lysis of erythrocytes.

• CD55 is also known as decay accelerating factor (DAF). It prevents assembly of the C3 and C5 convertases upstream of MAC formation in the complement cascade.

• GPI anchors CD55 to erythrocytes. A mutation in the PIGA gene of an early hematopoietic stem cell causes disruption of the GPI protein.

• CD59 is also called membrane inhibitor of reactive lysis (MIRL). It prevents formation of the membrane attack complex (MAC), which is the final stage in complement action.

PNH is an intrinsic, intravascular, acquired, hemolytic anemia.

Paroxysmal nocturnal hemoglobinuria (PNH) presents with a triad of hemolytic anemia, pancytopenia, thrombosis.

The thrombosis of PNH occurs in atypical veins, such as hepatic, abdominal, cerebral, and subdermal veins. The mechanism of the coagulopathy is not fully understood.

In paroxysmal nocturnal hemoglobinuria (PNH), the hemolytic anemia causes dark-colored urine at any point during the day, but most commonly in the morning. The concentration of urine in the morning produces a more drastic, noticeable change in color and makes the hemolysis appear more drastic overnight.

Laboratory confirmation of PNH includes demonstrating CD55-negative erythrocytes on flow cytometry.

Complications of paroxysmal nocturnal hemoglobinuria (PNH) can include:

• Budd-Chiari syndrome or hepatosplenomegaly due to hepatic vein thrombosis

• Bowel necrosis in the setting of abdominal venous thrombosis

• Thrombotic stroke in the setting of cerebral vein thrombosis

• Skin nodules in the setting of dermal vein thrombosis

Eculizumab is the treatment of choice for paroxysmal nocturnal hemoglobinuria (PNH). Eculizumab is an antibody to C5 complement component. It prevents C5 from cleaving to C5a and C5b, which are essential parts of the membrane attack complex. By inhibiting the complement system, it prevents the destruction of erythrocytes.

In addition to eculizumab, RBC transfusions, iron & folate supplementation may be required to treat the anemia. If the patient is on eculizumab, vaccination against N. meningitidis is required.

Paroxysmal nocturnal hemoglobinuria (PNH) carries a significant morbidity and mortality. Untreated, life expectancy is around 20 years after diagnosis (usually 30 - 40 years old). With eculizumab, life expectancy is similar to that of healthy counterparts.

G6PD

Glucose-6-Phosphate Dehydrogenase deficiency causes an acute, self-limited intravascular hemolysis due to oxidative injury to red blood cells.

G6PD deficiency results in decreased formation of NADPH via the hexose-monophosphate shunt. During states of oxidative stress NADPH is responsible for regenerating the reduced form of glutathione from its oxidized form. When glutathione is not regenerated the cell is more vulnerable to oxidative stress resulting in hemolysis.

G6PD deficiency is an X-linked recessive disorder and therefore occurs almost exclusively in men.

The two precipitants of hemolytic episodes in patients with G6PD deficiency are infection and medications.

Drugs that can precipitate a hemolytic episode in patients with G6PD deficiency can be remembered with the mnemonic "Hemolysis IS D PAIN":

• INH

• Sulfonamides

• Dapsone

• Primaquine

• Aspirin

• Ibuprofen

• Nitrofurantoin

Fava beans can increase intracellular oxidative stress and can therefore cause an acute attack in patients with G6PD deficiency who do not have any history of infection and are not taking any medications.

Patients with G6PD deficiency will present with sudden anemia, dark urine (hemoglobinuria) and jaundice that coincides with recent infection or starting of a new medication.

The most appropriate initial test for patients with suspected hemolytic episode due to G6PD deficiency is a peripheral blood smear to look for evidence of hemolysis especially Heinz bodies and "bite cells".

Patients with suspected G6PD deficiency will have the following on blood smear:

• Heinz bodies are intracytoplasmic aggregates of oxidized hemoglobin that can be seen with either Prussian blue and methylene blue staining.

• Bite cells are the result of splenic macrophages attempting to phagocytose the Heinz body.

The most definitive test for G6PD deficiency is quantification of G6PD with enzyme assay only AFTER resolution of the hemolytic episode as G6PD levels may be falsely normal if taken during an acute attack.

The most important treatment for patients with G6PD deficiency is supportive care and avoidance of precipitants of acute episodes since most attacks are self-limiting.

Pyruvate Kinase

Pyruvate kinase (PK) is an enzyme in the glycolysis pathway. It converts phosphoenolpyruvate (PEP) to pyruvate, producing one ATP.

Pyruvate kinase deficiency is inherited in an autosomal recessive fashion. Heterozygotes are not clinically affected. Other than spherocytic anemias, PK-deficiency is the most common congenital, chronic hemolytic anemia.

The chief symptoms of pyruvate kinase deficiency are due to hemolytic anemia. It can range in severity from fully compensated and asymptomatic to life-threatening. Symptoms of hemolytic anemia include:

• Failure to thrive

• Growth delay

• Cholecystolithiasis

• Frontal bossing

• Scleral icterus

• Splenomegaly

• Murphy's sign & upper right quadrant tenderness

• Chronic leg ulcers

Laboratory studies show extravascular hemolytic anemia with an appropriately increased reticulocyte count in response.

Pyruvate kinase deficiency is confirmed by genetic testing for the dysfunctional PK-LR gene, as well as deficient erythrocytic pyruvate kinase enzymatic activity.

Anyone with a congenital, extravascular, Coombs-negative hemolytic anemia should be tested for PK deficiency. Also, patients’ siblings should be tested as well.

Complications associated with PK-deficiency depend on disease severity. They are related to hemolytic anemia and repeat transfusions. Some include:

• Cholecystolithiasis in first decade of life in children with severe hemolysis

• Aplastic crisis with Parvovirus B19 infection

• Heart failure from severe anemia

• Iron overload from multiple transfusions

• Transfusion-related infections with HIV or hepatitis C

• Obstetric complications due to alloimmunization from repeated transfusions

Treatment for pyruvate kinase deficiency revolves around administering blood transfusions and managing the symptoms of hemolysis.

Splenectomy will reduce the severity of hemolysis, but it is not curative.

Macrocytic Anemia

Folate Deficiency

Inadequate intake of folate can lead to symptomatic folate deficiency within 4-5 months, as body stores are more limited compared to vitamin B12.

Drugs that block folate synthesis can also cause folate deficiency:

• Trimethoprim

• Pyrimethamine

• Methotrexate

• Phenytoin

The presentation of folate deficiency can be quite different from that of vitamin B12, as there are typically no neurological symptoms in folate deficiency.

Clinical vignettes often present the story of an alcoholic or an elderly patient on a "tea and toast" diet, deficient leafy vegetables, animal products & cereals.

Consumption of goat’s (instead of cow’s) milk may also contribute to folate deficiency, as goat’s milk has substantially less folate than cow’s milk.

Initial diagnostic work-up includes the following results:

• CBC shows megaloblastic, macrocytic anemia

• Serum folate is low

• B12 level will be normal; use this to rule-out B12 deficiency, as many signs & symptoms overlap

In some cases, a peripheral blood smear may be evaluated.

Peripheral blood smear will show features of megaloblastic, macrocytic anemia:

• Macro-ovalocytes

• Hypersegmented PMNs

In the event of a borderline serum folate level, a red cell folate level can be ordered.

In patients with borderline levels of both B12 and folate (or in patients with unexplained macrocytic anemia), "metabolite" testing can be ordered:

• Both serum homocysteine and methylmalonic acid (MMA) are elevated in vitamin B12 deficiency

• Only homocysteine is elevated in folate deficiency

Metabolite testing is more sensitive than serum vitamin levels alone.

The treatment for folate deficiency is oral folic acid for 1-4 months.

B12

A Quick Review of B12 Metabolism:

• B12 is bound by R-factor which protects it from gastric acidity

• In the duodenum, pancreatic enzymes hydrolyze the R-factor bond and B12 is bound by intrinsic factor (IF), which is synthesized by gastric parietal cells

• The B12-IF complex is absorbed in the terminal ileum

Vitamin B12 (cobalamin) is found in animal products (e.g. meat, fish).

Vitamin B12 (cobalamin) is synthesized by bacteria. Vitamin B12 cannot be synthesized by plants or animals.

Vitamin B12 (cobalamin) is a cofactor for:

• Methylmalonyl CoA mutase, which converts methylmalonyl CoA to succinyl CoA

• Homocysteine methyltransferase, which transfers methyl groups to homocysteine to form methionine

Vitamin B12 deficiency is typically discovered in the context of one of the following two clinical settings:

• Macrocytic anemia

• Neuropsychiatric symptoms

While both vitamin B12 deficiency and folate deficiency can cause macrocytic anemia, only B12 deficiency causes neuropsychiatric symptoms.

Vitamin B12 deficiency (unlike folate deficiency) can cause neuropsychiatric symptoms. These symptoms can be diverse and include:

• Memory Loss

• Irritability

• Dementia

• Paresthesia or ataxia

• In severe cases, subacute combined demyelination of the spinal cord

Vitamin B12 (cobalamin) deficiency may occur with:

• Malabsorption (e.g. Diphyllobothrium latum, sprue, enteritis, alcoholism)

• Absence of intrinsic factor (e.g. pernicious anemia or gastric bypass surgery)

• Absence of terminal ileum (due to Crohn disease or resection)

• Vegan diet

• Low gastric acid (due to PPI use)

Pernicious Anemia

Pernicious anemia is an autoimmune disease and is thus associated with other autoimmune diseases such as autoimmune thyroid disease, type 1 diabetes mellitus, and vitiligo.

Diagnosis is based on laboratory findings, and can be confirmed by low serum levels of B12. There are also important ancillary lab findings that may suggest the diagnosis:

• Macro-ovalocytes (MCV > 100) on peripheral blood smear (with or without anemia)

• Hypersegmented neutrophils on peripheral blood smear

• Increased serum methylmalonate

• Increased serum homocysteine

In settings when pernicious anemia is thought to be the underlying cause of B12 deficiency, serum levels of anti-intrinsic factor antibody can be obtained, and are confirmatory for the diagnosis.

Vitamin B9 (folate) deficiency can be distinguished from vitamin B12 deficiency on labs by:

Vitamin B9 (folate) deficiency	Vitamin B12 deficiency
- Normal methylmalonic acid - Elevated homocysteine	- Elevated methylmalonic acid - Elevated homocysteine

Elevated levels of homocysteine seen in folate and vitamin B12 deficiency cause endothelial cell damage and can result in atherosclerosis and thrombosis.

While the liver stores a 3-4 year supply of vitamin B12, it only stores a 3-4 month supply of vitamin B9 (folate). Thus, while it can take years for a patient to become B12 deficient, it only takes months for a patient to develop a folate deficiency.

Complications: increased risk for gastric cancer

Diagnosis

B12 deficiency therefore causes ineffective erythropoiesis due to delayed nuclear maturation, resulting in decreased transition to mature red blood cell (RBC) forms and high numbers of immature megaloblasts in the bone marrow. Increased intramedullary hemolysis of these megaloblasts releases heme, causing indirect hyperbilirubinemia, which may manifest as jaundice. Hemolysis also releases the intracellular enzyme lactate dehydrogenase (LDH), raising serum levels. Total RBC count and reticulocyte count will be low. Patients may also develop thrombocytopenia and leukopenia with hypersegmented polymorphonuclear cells.

Treatment

The initial treatment of choice for vitamin B12 deficiency is parenteral cobalamin (B12) especially in patients with neurologic sequelae. Once vitamin B12 levels are normalized, the patient can be switched to oral (or continue parental).

Penias

Pancytopenia

Pancytopenia is defined as a decrease in the number of circulating cells in all 3 cell lines (anemia, leukopenia, and thrombocytopenia). The signs and symptoms of pancytopenia have to do with the decrease in individual cell lines:

• Anemia: fatigue, pallor, dyspnea on exertion and other symptoms of cardiopulmonary compromise

• Leukopenia: frequent infections (especially bacterial such as sepsis, pneumonia, and UTIs; fungal infections can be the most life-threatening)

• Thrombocytopenia: petechiae, bleeding

After pancytopenia is confirmed by a CBC, a peripheral blood smear is done to see if this information may hint at the cause of the pancytopenia. For example:

• Ringed sideroblasts may suggest copper deficiency or other etiologies

• Hypersegmented neutrophils suggest a possible folate/vitamin B12 deficiency

• Immature white blood cells or hairy cells suggest a leukemia or lymphoma

• Dacrocytes (“teardrop cells”) may suggest a myelofibrotic pathophysiology

While the reticulocyte count is part of the CBC, it deserves a separate discussion here because it is important in determining whether the pancytopenia is caused by failure of the bone marrow. The reticulocyte count will be low in the case of marrow failure.

In adults, the two most common causes of significant pancytopenia are leukemia (including specific leukemias as discussed below) and aplastic anemia. The definitive test for distinguishing between these two causes is a bone marrow biopsy.

In children, leukemia and aplastic anemia are also considered as causes of pancytopenia, but you must also consider congenital causes such as Fanconi’s anemia. Fanconi’s anemia will present with other congenital abnormalities (short stature, cafe au lait spots, abnormal thumbs) or an early presentation of cancer or strong family history of cancer. It is ultimately diagnosed with DNA analysis.

There are 3 causes of pancytopenia that are much more common in patients with sickle cell anemia: aplastic crisis (usually caused by Parvovirus B19 infection), splenic sequestration, and hyperhemolytic crisis (associated with multiple transfusions).

One of the most important tests in differentiating causes of acute pancytopenia in sickle cell disease is the reticulocyte count:

• Aplastic crisis: Low

• Splenic sequestration: High

• Hyperhemolytic crisis: High

Thrombocytopenia

Thrombocytopenia is defined as a platelet count < 150,000/uL.

The most relevant clinical platelet levels are:

• <10,000/uL for risk of spontaneous bleeding

• <50,000/uL for risk of surgical bleeding

Thrombocytopenia can arise due to:

• Platelet underproduction

• Peripheral platelet destruction

• Dilution (in the setting of RBC transfusion)

• Splenic sequestration

Platelet underproduction usually occurs along with broader bone marrow suppression, causing pancytopenia, but isolated thrombocytopenia may also be seen. Some specific situations include:

• Infection- particularly viral (HIV, measles, mumps, rubella, EBV, parvovirus, HepC); bacterial sepsis can also cause thrombocytopenia

• Drugs- while some drugs can cause peripheral destruction, others cause bone marrow toxicity, namely quinine, linezolid, and valproate

• Alcohol

• Nutritional deficiencies, specifically folate, vitamin B12, and copper

• Bone marrow disorders, such as myelodysplastic syndromes, leukemias, and paroxysmal nocturnal hemoglobinuria

Platelet peripheral destruction can be antibody-mediated or due to over-consumption. Some causes of peripheral platelet destruction can include:

• Immune thrombocytopenia (ITP) - antibody mediated

• Drugs- antibiotics are commonly implicated, specifically sulfonamides, ampicillin, piperacillin, vancomycin, rifampin; anti-epileptics such as carbamazepine and phenytoin are also common precipitants

• Heparin Induced Thrombocytopenia

• TTP/HUS

Consumption of tonic water can cause thrombocytopenia because tonic water contains quinine, one of the most common etiologies of drug-induced thrombocytopenia.

The initial steps of the diagnostic process for thrombocytopenia involve:

• Repeating CBC to confirm presence of genuine thrombocytopenia

• Reviewing peripheral blood smear to rule out pseudothrombocytopenia (i.e. falsely lower platelet counts due to platelet clumping) or to narrow the differential by discovering concomitant RBC abnormalities

Adult patients with unexplained, new-onset thrombocytopenia should be tested for HIV and HCV.

Management of thrombocytopenia is typically etiology-specific, but there are some general principles that apply in all cases:

• Patients with platelet counts <50,000/uL should not participate in extreme athletics

• Caution should be exercised in using anti-platelet medications (e.g. aspirin, NSAIDs) in patients with thrombocytopenia

• Most surgical procedures can be performed as long as the platelet count is above 50,000/uL; for neurosurgical procedures, there is a preference for the platelet count to be above 100,000/uL

• Platelet transfusion should be performed in the setting of active bleeding to keep platelet account above 50,000/uL, and above 100,000/uL if there is concern about intra-cranial bleeding

Lymphocytopenia

Lymphocytopenia is defined as an absolute lymphocyte count of < 1000 cells/microliter in adults and < 3000 cells/microliter in children. The most common subset of lymphocytopenia is a decrease in T lymphocytes. B lymphocytes are less often decreased, and NK lymphocytopenia is the least common type.

Chronic glucocorticoid usage is a cause of lymphocytopenia. Other more common causes of lymphocytopenia are sepsis (bacterial or fungal), postoperative state, malignancy, cancer treatment (chemotherapy or radiation), malnutrition, and trauma or hemorrhage.

Neutropenia

Neutropenia is defined as an absolute neutrophil count (ANC) of < 1500 cells/microliter. Severe neutropenia is an ANC < 500 cells/microliter. Idiopathic neutropenia is more common in minorities, especially African Americans, as they naturally have a lower level of neutrophils in their blood.

The drugs most commonly implicated in causing neutropenia are antithyroid drugs (methimazole, carbimazole, propylthiouracil), sulfasalazine, clomipramine, trimethoprim-sulfamethoxazole, and dipyrone combined with analgesics. Almost half of all cases are caused by methimazole, sulfasalazine, and trimethoprim-sulfamethoxazole.

Neutropenia can also be caused by nutritional deficiencies, toxins, collagen vascular diseases (lupus, rheumatoid arthritis), infections, hematologic conditions (like myelodysplasia), and benign ethnic neutropenia (inherited due to race). Notably, conditions causing neutropenia in the blood only increase the risk of infection when there is also a decrease in the neutrophils in the bone marrow.

Neutropenia is often asymptomatic or presents with signs and symptoms of the underlying disorder causing it, and is thus usually discovered incidentally on a complete blood count (CBC) with auto differential. As stated above, neutropenia is defined as an absolute neutrophil count of <1500/microliter.

Neutropenic patients with no fever are safer outside of a hospital than inside one, and no treatment is necessary (other than for underlying disorders). However, if a neutropenic patient presents with fever, the patient must immediately be hospitalized and treated with empiric antibiotics immediately after obtaining blood cultures and within 60 minutes of presentation. The empiric antibiotic regimen will be dependent on patient risk factors, likely infection, patient allergies, and other factors.

ITP

Immune thrombocytopenia (ITP) is an acquired thrombocytopenia mediated by antibodies to GpIIb/IIIa and can be triggered by an associated condition (secondary ITP) or can occur as a standalone problem (primary ITP).

Secondary ITP is frequently associated with the following conditions:

• HIV

• Hep C

• Systemic Lupus Erythematosus (SLE)

• Acute or subacute viral infection

ITP may remain clinically silent, and thrombocytopenia is seen on routine screening, especially in those experiencing only a mild drop in platelet counts. For those with more severe disease, the clinical manifestations are related to bleeding: ecchymoses, petechiae, GI bleeding, heavy menstrual bleeding.

ITP typically occurs as isolated thrombocytopenia without any associated hematologic abnormalities.

Diagnosis

ITP is primarily a diagnosis of exclusion and thus diagnostic evaluation involves investigation of possible alternative causes of thrombocytopenia. Routine testing for anti-platelet antibodies is not recommended, given its low sensitivity and specificity.

Bone marrow biopsy is rarely done to diagnose ITP. However, it may be performed to exclude other potential diagnoses. Bone marrow examination will show increased megakaryocytes, which appear large or immature.

Treatment

ITP management is guided based on platelet counts and presence or absence of bleeding. The disease is typically self-limited in children and will resolve spontaneously within 6 months.

For adults with platelet counts > 30,000/uL and without significant risk factors for bleeding or current bleeding, treatment is not recommended.

Adults with a platelet count < 30,000 or who are actively bleeding require treatment with corticosteroids and/or IVIG.

Platelet transfusions in patients with ITP are only given if there is severe, life-threatening bleeding (e.g. intracranial or gastrointestinal). As these complications are exceedingly rare, platelet transfusions are hardly ever used in these patients.

For patients who experience clinically significant bleeding with persistent thrombocytopenia despite first-line treatment with glucocorticoids and IVIG:

• The preferred second-line option is splenectomy

• If splenectomy is contraindicated, rituximab can be administered

HIT

Heparin-induced thrombocytopenia (HIT) is an immune-mediated reaction that occurs following exposure to any heparin products, resulting in a paradoxically pro-thrombotic state.

The pathophysiology of HIT involves the development of auto-antibodies to the platelet factor 4 (PF4):heparin complex; the auto-antibodies cross-react with platelets causing peripheral activation (thrombosis) and destruction (thrombocytopenia).

HIT can occur in any patient population with exposure to any heparin products, but certain situations are considered higher risk:

• Unfractioned vs. low-molecular weight heparin

• Higher doses of heparin

• Female gender

• Recent surgery

HIT typically manifests initially as thrombocytopenia 5-10 days following exposure to a heparin product, though a minority of patients may have thrombosis as the presenting finding.

The timing of HIT follows a very characteristic pattern:

• The majority of cases are seen 5-10 days following exposure to a heparin product

• Early-onset HIT (within 24 hours) may be seen if a patient has been exposed to a heparin product at some point within the past 3 months and has circulating HIT antibodies

The thrombocytopenia seen with heparin induced thrombocytopenia usually entails a drop in the platelet count of >50%.

Thrombosis occurs in about half of patients with HIT, with venous more common than arterial thrombosis. Common sequelae include:

• Skin necrosis at the site of heparin injections

• Limb gangrene

• Organ ischemia or infarction (if arterial thrombosis is present)

Diagnosis of HIT begins with clinical suspicion, including use of a 4-T score, which provides a pre-test probability. Patients meeting the following parameters have a high likelihood of testing positive for HIT:

• Thrombocytopenia: drop in platelet count of >50%, with a nadir in platelet count >20,000/uL

• Timing: drop in platelet count 5 - 10 days following exposure to heparin OR within 24 hours if patient has had prior exposure within the past 3 months

• Thrombosis or other sequelae: confirmed new thrombosis

• OTher causes for thrombocytopenia: not present

Diagnosis

The diagnosis can be supported by laboratory finding, which include immunoassays and functional assays.

• Screen for HIT with anti-PF4 antibodies in the serum. Typically utilized first, this test has a high sensitivity, but low specificity.

• Confirm HIT with serotonin-release assay (SRA), which is the gold-standard for diagnosis of HIT and has both high sensitivity and specificity.

Treatment

The first step in management of HIT is to stop administration of all heparin products.

For all patients with suspected HIT, anti-coagulation with a non-heparin anti-coagulant is recommended. Options include:

• Direct-thrombin inhibitors (e.g. argatroban, bivalirudin)

• Fondaparinux

The choice of specific anti-coagulant is based on patient-specific considerations.

• For patients with normal hepatic and renal function, argatroban is typically used

• For patients with renal dysfunction, argatroban is typically used as it is metabolized hepatically

• For patients with hepatic dysfunction, fondaparinux is preferred

• For patients with hepatic and renal dysfunction, either argatroban or bivalirudin can be used at reduced doses

TTP

Thrombotic thrombocytopenic purpura (TTP) and Hemolytic uremic syndrome (HUS) are syndromes characterized by:

• ​Microangiopathic hemolytic anemia

• Thrombocytopenia

Although some experts create distinctions between TTP and HUS, the presenting features are essentially the same and TTP/HUS is therefore considered two diseases on a single continuum. See below for more details.

Classically distinctions were made based on predominance of neurologic vs. renal symptoms:

• In TTP, neurologic symptoms are common and renal symptoms are mild, if present.

• In HUS, acute renal failure is the predominant feature and neurologic symptoms are rare.

However, many patients (up to half) present with neither neurologic abnormalities nor renal failure. Others present with both symptoms. Therefore, the difference between TTP and HUS is minimal.

TTP/HUS (Thrombotic thrombocytopenic purpura / hemolytic uremic syndrome) should at least be considered in all patients with thrombocytopenia and anemia

TTP/HUS are characterized by the classical pentad of signs/symptoms:

• Microangiopathic hemolytic anemia (MAHA), which is a hallmark of the disease. Schistocytes are seen on peripheral smear due to non-immune hemolysis of erythrocytes.

• Thrombocytopenia

• Acute kidney injury

• Neurologic abnormalities--typically, altered mental status

• Fever (typically not high-grade, and may even be absent)

It is rare for all 5 of these features to actually be present in the setting of disease.

TTP/HUS can occur in the setting of:

• Bloody diarrhea caused by shiga toxin-producing bacteria (e.g. E. Coli O157:H7)

• Pregnancy

• Cyclosporine

• Gemcitabine

Diagnosis

For treatment purposes, only the presence of MAHA (microangiopathic hemolytic anemia) and thrombocytopenia are required to make a presumptive diagnosis of TTP/HUS.

Further laboratory studies will include:

• Peripheral blood smear - should demonstrate schistocytes, and alternative RBC morphologies may suggest alternative diagnoses

• Serum LDH and Haptoglobin - elevated LDH, decreased haptoglobin will confirm presence of hemolysis

• ADAMTS13 activity level - A value <10% is highly supportive of TTP/HUS, but cannot be used to confirm or rule out the diagnosis

Treatment

Treatment should be initiated whenever there is reasonable suspicion for TTP/HUS as the condition left untreated is invariably fatal.

Plasma exchange is the treatment for TTP/HUS and should be continued daily until platelet count & LDH normalize.

Because TTP/HUS is a medical emergency, if plasma exchange is not immediately available, plasma infusion can be utilized as a temporary measure.

Bleeding Disorders

VWD

von Willebrand disease (vWD) is the most common inherited bleeding disorder, and is characterized by impaired hemostasis due to defects in von Willebrand factor (vWF).

vWF plays two important roles in hemostasis:

• Adheres both to platelets and subendothelial components, thereby allowing for platelet clumping at the site of vessel injury (primary hemostasis)

• Binds factor VIII and extends its otherwise brief half-life in the bloodstream

vWD can become symptomatic at any age, and should especially be considered in any of the following clinical scenarios:

• Difficult to control epistaxis

• Excessive bleeding following invasive procedures

• Menorrhagia

• Excessive peripartum bleeding

Diagnosis

Initial diagnostic tests recommended for evaluation of suspected vWD include:

• Plasma vWF antigen

• Plasma vWF activity (ristocetin cofactor assay)

• Factor VIII activity

Patients with vWD will have the following laboratory findings:

• Decreased plasma vWF antigen and/or decreased plasma vWF activity

• Factor VIII activity that is low or low-normal

Following the diagnosis of vWD, the disease is further classified by two additional laboratory assays:

• vWF multimer assay

• Ristocetin-induced platelet aggregation

Treatment

The management of vWD is dictated by the specific disease sub-type, though most patients should receive a trial of desmopressin (DDAVP). For patients with minor bleeding, IV or intra-nasal DDAVP is typically appropriate.

For major bleeding or surgery, patients may require infusion of vWF concentrate.

Hemophilia A and B

Hemophilia A and B are X-linked recessive disorders caused by a deficiency in clotting factors. As such, patients are almost exclusively male.

Hemophilia A is caused by a deficiency in Factor VIII. Hemophilia A occurs in about 1 in 5,000 males with approximately 40% occurring in families with no history of the disease.

Hemophilia B is caused by a deficiency in Factor IX. Hemophilia B affects about 1 in 30,000 males.

In patients with hemophilia, the following coagulation findings are present:

• Normal bleeding time

• Normal PT

• Prolonged PTT

In hemophilia, the prolonged aPTT corrects with a mixing study. A mixing study supplies deficient clotting factors and reassesses the coagulation studies. It differentiates between factor deficiency (e.g., hemophilia) and the presence of a clotting inhibitor (e.g., antiphospholipid antibody, which does not correct with the mixing study). Therefore, you should measure factor VIII & IX levels in any male with a prolonged aPTT that corrects with a mixing study.

Mild Hemophilia may become clinically apparent after surgery (e.g. routine dental procedures) or trauma. It is an x-linked disorder.

Symptoms of hemophilia include hemarthroses (spontaneous bleeding into joints) and intramuscular hematomas. Note that this is distinctly separate from the presentation of patients with platelet deficiencies (mucosal hemorrhage, petechiae, purpura).

Hemophilic arthropathy is a complication of recurrent hemarthroses in hemophiliacs, in which hemosiderin deposition leads to joint synovitis and tendonitis. Suspect this diagnosis in a patient with a history of multiple hemarthroses who presents with chronic worsening pain and stiffness of a joint.

Head trauma can be particularly life threatening in these patients, as intracranial bleeding is a common cause of death for hemophiliacs.

Treatment

Hemophilia A patients are given Factor VIII during acute bleeding episodes. In minor disease, DDAVP may be helpful for patients, as it increases the activity of Factor VIII.

Hemophilia B patients are treated with factor IX concentrates in situations of severe bleeding. DDAVP does not help Hemophilia B patients.

Hereditary Telangiectasia

Red papules over the trunk and lips represent cutaneous arteriovenous malformations. They can be seen in hereditary telangiectasia, an autosomal dominant disorder characterized by recurrent epistaxis, and telangiectasias. Patients with hereditary telangiectasia are not predisposed to skeletal muscle hematomas.

TTP

TTP
Pathophysiology	↓ ADAMTS13 level → uncleaved vWF multimers → platelet trapping & activation Acquired (autoantibody) or hereditary
Clinical features	Hemolytic anemia (↑ LDH, ↓ haptoglobin) with schistocytes Thrombocytopenia (↑ bleeding time, normal PT/PTT) Sometimes with: Renal failure Neurologic manifestations Fever
Management	Plasma exchange Glucocorticoids Rituximab

Factor V Liden

The most commonly found disorder is factor V Leiden (FVL), especially in Caucasian patients (4%-5% prevalence). Most patients with FVL have an autosomal dominant point mutation in the gene for factor V that makes it unable to respond to activated protein C, an innate anticoagulant. This mutation leads to slowed degradation of procoagulant active factor V, leading to continued thrombin formation and to slowed degradation of active factor VIII. Prothrombin time and activated partial thromboplastin time can be normal as the major procoagulant effects are due to continued thrombin formation; the elements of the coagulation cascade that can be assessed by these laboratory tests are less likely to be predominantly affected.

Patients who inherit FVL are at an increased risk for DVT and PE, although not all express this phenotype as most are heterozygous. Those who are homozygous are at an even greater risk.

Platelet Diseases

Platelet disease (qualitative or quantitative) causes an increased bleeding time and superficial bleeding.Examples of superficial bleeding are:

• Petechiae

• Bleeding gums

• Purpura

• Epistaxis

• Metromenorrhagia

• Excessive bleeding following circumcision

Deeper bleeding such as hemarthrosis and hematomas are not typically seen in platelet disorders (they are symptoms of coagulation cascade defects).

The most common cause of platelet dysfunction is pharmaceuticals, either as the desired effect or as an adverse effect. Some drugs that can block platelet function are:

• Aspirin (most common) - irreversibly blocks COX1 preferentially over COX2, thereby blocking thromboxane A2

• NSAIDs: reversibly block COX1 > COX2

• Dipyridamole

• ADP-receptor blockers:clopidogrel,ticlopidine

• GpIIb/IIIa blockers:abciximab,eptifibatide

Bernard-Soulier

Bernard-Soulier syndrome is a genetic deficiency in the GPIb receptor, which normally binds vWF (von Willebrand Factor). Therefore, platelets cannot adhere to subendothelial collagen & form a plug. Read more about normal coagulation.

In Bernard-Soulier syndrome, platelets do not clot in response to ristocetin.

In the laboratory, ristocetin assays force vWF to bind GPIb receptors. Therefore, it tests the availability of both vWF and GpIb. Similarly, von Willebrand Disease (vWD: deficiency of vWF) also does not clot in a ristocetin assay. vWD can appear as a defect in platelet function because platelets require vWF for initial aggregation.

The platelet count is characteristically low in Bernard-Soulier syndrome. Also, the platelets are large, almost the size of erythrocytes. They are so large they are often missed in automated counts.

Glanzmann

Glanzmann thrombasthenia is a genetic deficiency of the GPIIb/IIIa receptor, which normally binds fibrinogen to link two adjacent platelets together. Read more about normal coagulation.

In Glanzmann thrombasthenia, platelets do aggregate in a ristocetin assay. Contrast this to Bernard-Soulier syndrome & von Willebrand Disease.

Type I Glanzmann thrombasthenia is a complete loss of GPIIb/IIIa and is more severe than type II. Type II is an incomplete loss, and some function is preserved.

In renal failure, uremia-induced platelet dysfunction can cause coagulopathy. Vigorous dialysis is generally the best therapy.

Therapy options generally depend on the etiology and can include:

• Desmopressin

• Estrogens, most commonly in uremic-induced bleeding

• Antifibrinolytic agents (eg, tranexamic acid, aminocaproic acid) following dental extractions

• Recombinant factor VIIa, especially in congenital disorders

• Platelet infusions are reserved for cases of severe bleeding

Platelet infusions should be used sparingly in cases of genetic platelet defects (Bernard-Soulier disease and Glanzmann thrombasthenia) because the patient can form antibodies to their deficient protein (GPIb or GPIIb/IIIa).