Bleeding disorders

Question 1

Idiopathic thrombocytopenic purpura (ITP)

Answer 1

produces autoantibodies for GPIIb/IIIa, binds to platelets then the complex is removed by splenic macrophages; labs show increased megakaryocytes in the BM

Question 2

Heparin-induced thrombocytopenia

Answer 2

patient develops antibody to heparin-PF4 complex which triggers platelet activation and aggregation; venous thrombosis in 10-30% of cases

Question 3

Thrombotic thrombocytopenic purpura (TTP)

Answer 3

autoantibody to ADAMTS-13, ultra-long VWF bind platelets, cause activation, form thrombi, shear RBCs -> schistocytes; pentad of neurologic and renal symptoms, fever, thrombocytopenia, and microangiopathic hemolytic anemia; treat with plasmapheresis

Question 4

Hemolytic uremic syndrome (HUS)

Answer 4

occurs in young children; E coli or Shiga toxin damages endothelial cells causing thombi formation -> schistocytes; triad of thrombocytopenia, microangiopathic hemolytic anemia, renal failure

Question 5

Disseminated intravascular coagulation (DIC)

Answer 5

systemic activation of coagulation secondary to an underlying condition -> schistocytes; consume clotting factors and platelets, activate fibrinolysis, resulting in systemic bleeding; prolonged bleeding time, PT, PTT time and lower platelet count

Question 6

Bernard Soulier syndrome

Answer 6

adhesion defect due to mutation in GP Ib-IX-V; thrombocytopenia and giant platelets.

Question 7

Glansmann thrombasthenia

Answer 7

aggregation defect due to mutation in GP IIb -IIIa.

Question 8

von Willebrand disease

Answer 8

most common bleeding disorder; quantitative or qualitative defieiency of vWF; bleeding time longer, APTT may be longer cause factor VIII is not protected by vWF

Question 9

Hemophilia A

Answer 9

deficiency of factor VIII; X-linked recessive

Question 10

Hemophilia B

Answer 10

deficiency of factor IX; X-linked recessive

Question 11

Hemophilia C

Answer 11

deficiency of factor XI; autosomal recessive

Question 12

Vitamin K deficiency

Answer 12

deficiencies in factor II, VII, IX, X, protein C, S, Z; prolonged PT and APTT, normal TCT and fibrinogen level. Only PT prolonged in early deficiency (factor VII has shortest half-life)

Question 13

Liver disease

Answer 13

multiple coagulation factor deficiencies (liver site of synthesis of coagulation factors); prolonged PT, APTT, TCT

Question 14

Factor V (Leiden) mutation

Answer 14

factor V is resistant to degradation by protein C -> hypercoagulability state

Question 15

Coagulation

Answer 15

physiologic -> hemostatic plug

Question 16

Thrombosis

Answer 16

pathologic (inappropriate platelet aggregation, thrombophilia) -> emboli

Question 17

Anemic infarction (most common)

Answer 17

organs with single blood supply (thrombus/embolus occludes the artery -> area of hypoperfusion)

Question 18

Hemorrhagic infarction

Answer 18

organs with a dual blood supply (embolus occludes one artery, other artery/vein continues to perfuse but at a lower rate)

Question 19

Embolism

Answer 19

obstruction in a blood vessel due to a blood clot or other foreign matter that gets stuck while traveling through the bloodstream

Question 20

Desmopressin

Answer 20

drug to treat vWF disease, stimulates release of vWF