Platelet Disorders

Question 1

Bernard-Soulier syndrome

Answer 1

PC: Decrease
BT: Increase
Mechanism and comments: Defect in platelet plug formation.
Decreased GpIb -> defect in platelet-to-vWF adhesion.

Question 2

Glanzmann’s thrombasthenia

Answer 2

PC: -
BT: Increase
Mechanism and comments: Defect in platelet plug formation.
Decreased GpIIb/IIIa -> defect in platelet-to-platelet aggregation.
Labs: blood smear shows no platelet clumping.

Question 3

Idiopathic thrombocytopenic purpura (ITP)

Answer 3

PC: Decrease
BT: Increase
Mechanism and comments: Defect: anti-GpIIb/IIIa antibodies->splenic macrophage consumption of platelet/antibody complex.
decreased platelet survival.
Labs: Increased megakaryocytes.

Question 4

Thrombotic thrombocytopenic purpura (TTP)

Answer 4

PC: Decrease
BT: Increase
Mechanism and comments: Deficiency of ADAMTS 13 (vWF metalloprotease) -> decreased degradation of vWF multimers.
Pathogenesis: Increased large vWF multiners -> Increased platelet aggregation and thrombosis.
Decreased platelet survival.
Labs: schistocytes, Increased LDH.
Symptoms: pentad of neurologic and renal symptoms, fever, thrombocytopenia and microangiopathic hemolytic anemia.