05 Platelet Disorders

Inherited

Glanzman's

• superficial bleeding

• nl aggregation with ristocetin test

Bernard

• large platelets on smear

• abnormal ristocetin assay

Wiskott- Aldrich

Acquired

• ITP

• TTP

• HUS

• DIC

• Uremia

• thrombocytopenia

• vWF

• Hayde's

ITP

• don't live as long as they should = low number

• macrophages clear antibody bound platelets

• platelet thrombi: platelet low, coagulation factors not consumed

TTP

• much more dangerous

• low platelets, thrombosis

• thrombus form in small vessels, consumes platelets, thrombocytopenia

• TTP: build up of platelets and RBC, obstruction

• small vessel occlusion in CNS

• thrombi primarily made of platelets, do not consume clotting factor

• platelet thrombi: platelet low, coagulation factors not consumed

HUS

• distinguish from TTP: no fever or CNS symptoms (TTP only with kidney)

• platelet thrombi: platelet low, coagulation factors not consumed

DIC

• both platelets and fibrin, increased PT, PTT

• TF activate coagulation cascade

• sepsis: high levels of cytokines and endotoxins

• every blood test abnormal

• platelet thrombi: platelet low, coagulation factors not consumed

Uremia

• caused by toxins, not platelets

Thrombocytopenia

Von Willebrand

• heavy periods common early presentation

• ristocetin test normal in glanzman

• ristocetin test also abnormal in Bernard

Hayde's

• aortic stenosis: increased risks of angiodysplasia

• overactivity of ADAMST13, breaking down multimers, causing VWF to be less efficient