11 Microcytic Anemia

Measurements

• liquid plasma at top of tube

• % occupied by red cells compared to whole = hematocrit

• average RBC

• MCV: mean amount of volume in RBC, not total volume

• MCHC: ratio of MCH/MCV

• MCV most important

• iron deficiency/anemia of chronic disease: both microcytic and normocytic

Microcytic Anemia

• when not enough hemoglobin, RBC precursor undergoes extra devision, smaller RBC

• histology: larger pale areas

• if any of the 3 main components deficient, anemia

• protoporphyrin: surrounds iron in heme

• loss of heme: lead poisoning, sideroblastic anemia

Iron Deficiency

• absorbed in 2 forms

• heme: iron in center of heme, found in flesh of other animals

• absorbed in duodenum

• enterocyte uptake main way of regulation

• ferroportin controls amt of iron released from duodenal cells into body

• % sat: iron/TIBC

Cause

• new born babies deplete iron store from mother in 6 months of age

• loss of acid: gastrectomy/PPI

• loss most common cause

• colon cancer: very important/dangerous. Initial presentation

• unexplained iron deficiency anemia: colon cancer workup

• losing more iron than taking in

• % sat low under pregnancy/OCP use, misleading for iron deficiency anemia

• use ferritin for diagnosis in pregnancy/OCP

Pathogenesis

• 1st thing: deplete body storage

• eventually ferritin storage depleted, and serum iron begin to drop

Diagnosis

• fewer RBC produced

• everything is low

• initially make fewer RBC but maintain size

• some cells find iron to form normal amount of hemoglobin = normal in size

• other cells deficient in iron = small

• can be seen in any nutritionally caused anemia

• thalassemia: normal, deficient production of globin chain, all RBC same problem

• not enough iron around: elevated protoporphyrin levels

• hemochromatosis: iron overload

Treatment

Anemia of Chronic Diseases

• mild anemia

• severe anemia: unlikely microcytic

• rising cytokines

• RBC don't live as long

• EPO rise higher in iron deficiency anemia compared to rise in chronic disease anemia

• ferroportin lets iron out in enterocytes and macrophages

• rise in ferritin: opposite of iron deficiency

Diagnosis

• in real life: ferritin is acute phase reactant, increase not representative. Step 1, ferritin is chronic disease

• TIBC: low, total body storage is high

• hemochromatosis: iron overload

Lead Poisoning

• battery: classic

• heme derived from succinyl coa and glycine

• inhibition of D-ala dehydratase and ferrochelatase: low Heme

• increased activity of ALA synthase: build up of D-ALA

• protoporphyrin: also used to screen iron deficiency

Symptoms

• DMSA aka succimer

Sideroblastic anemia

• B6 co factor

• lead poisoning: underproduction of protoporphyrin

• B6 activates available ALA synthase

Diagnosis

• lead poisoning sideroblastic: can have high protoporphyrin