Platelet disorders

Question 1

Bernard-Soulier syndrome

Answer 1

dec. in Gp1b –> defect in platelet-to-vWF adhesion

Question 2

Glanzmann thrombasthenia

Answer 2

dec. GpIIb/IIIa –> defect i platelet-to-platelet adhesion

Question 3

Immune thrombocytopenia

Answer 3

defect in an anti-GpIIb/IIIa antibodies –> splenic macrophage consumption of platelet/antibody complex

Question 4

lab findings of immune thrombocytopenia

Answer 4

incr. megakaryocytes on bone marrow biopsy. decreased platelet survival

Question 5

thrombotic thrombocytopenic purpura molecular bio defect

Answer 5

inhibition of ADAMTS 13, a vWF metalloprotease –> dec. degradation of vWF multimers

Question 6

pathology of TTP

Answer 6

large vWF –> more platelet adhesion –> more platelet aggregation / thrombosis, dec. platelet survival

Question 7

symptoms of TTP (5)

Answer 7

1) neuro symptoms
2) renal symptoms
3) fever
4) thrombocytopenia
5) microangiopathic heolytic aemia

Question 8

treatment of TTP

Answer 8

exchange transfusion / steroids

Question 9

inheritance of VWF disease

Answer 9

autosomal dominant

Question 10

treatment of vWF

Answer 10

DDAVP –. release vWF stored in endothelium

Question 11

DIC presentation

Answer 11

widespread activation of clotting leads to deficiency of clotting factors –> bleeding factors

Question 12

causes of DIC (7)

Answer 12

1) Sepsis (gram-negative)
2) Trauma
3) Obstretric complications
4) Pancreatitis
5) Malignancy
6) Nephrotic syndrome
7) Transfusion

Question 13

DIC labs

Answer 13

• schistocytes
• incr. fibrin split products = D-dimers
• dec. fibrinogen
• dec. factors V/VIII

Question 14

consequence of prothrombin gene mutation

Answer 14

mutation in 3’ UTR –> incr. production of prothrombin –> incr. plasma levels + venous clots

Question 15

what’s the paradox of the antithrombin deficiency?

Answer 15

inherited deficiency of antithrombin, BUT

• no direct effect on PT, PTT, or thrombin time
• diminishes increase in PTT following heparin administration

Question 16

how can antithrombin deficiency be acquired?

Answer 16

renal failure/ neprhotic syndrome –> antithrombin loss in urine –> incr. in factors II / X

Question 17

mnemonic for protein C?

Answer 17

protein C CANCELS COAGULATION

Question 18

clinical problem with protein C / S deficiency?

Answer 18

administration of warfarin –> risk of thrombotic skin necrosis + hemorrhage

problem: dec. ability to inactive factors V / VIII