Platelet Disorders

Question 1

Acute ITP

Answer 1

Only found in children, the onset is sudden, reading worsens as platelet count drops. Shows petechiae, ecchymoses after mild trauma. The smear shows giant platelets due to increased levels of thrombopoetin

Question 2

Chronic ITP

Answer 2

Found in adults with insidious onset, more common in females.

Question 3

Alloimmune thrombocytopenia

Answer 3

Due to patient’s with platelet antigens HPA 1b receiving platelets from people with the HPA-1a antigen and producing antibodies

Question 4

Thrombotic thrombocytopenic Purpura

Answer 4

Caused by the abnormal presence of unusually large multimers of VWF, sporadic causes are from antibody or toxin inhibiting the ADAMTS 13 enzyme, the chronic form may result from a chronic deficiency
The multimers induce platelet aggregation, causing platelet consumption and occlusion
Presents with petechiae and neurological symptoms

Question 5

Hemolytic uremic syndrome

Answer 5

Renal vasculature has vascular lesions, usually found on children 4 to 12, following an upper respiratory tract infection
Patient show abnormal bleeding, particularly G.I. tract bleeding; the platelets synthesize less thromboxane A2 and blood vessels produce more playlet inhibitory prostaglandin

Question 6

Immune thrombocytopenic Purpura

Answer 6

Two types: 1) self-limiting form seen mainly in children, 2) a chronic form seen mainly in adults
Caused by auto antibodies to platelets, the target of which is the glycoprotein 2B/3A complex, and sometimes the megakaryocytes in the bone marrow