Internal Medicine Exam Hematology 2 — Questions and Answers
Question 1: A patient has a prolonged PT but normal aPTT. Deficiency of which coagulation factor is most likely responsible?
- Factor VIII
- Factor IX
- Factor VII (Correct answer)
- Factor XII
Correct answer: Factor VII
Factor VII is the only coagulation factor exclusive to the extrinsic pathway; its deficiency prolongs PT without affecting aPTT.
Question 2: Heparin-induced thrombocytopenia (HIT) typically develops at what time point after heparin initiation?
- Within 24 hours
- 5-10 days after starting heparin (Correct answer)
- Only after 4 weeks of therapy
- Immediately upon re-exposure regardless of timing
Correct answer: 5-10 days after starting heparin
Classic HIT (type II) develops 5-10 days after starting heparin due to the time required for antibody formation against platelet factor 4-heparin complexes.
Question 3: Von Willebrand disease most characteristically presents with which bleeding pattern?
- Hemarthroses and deep muscle hematomas
- Mucocutaneous bleeding such as epistaxis and menorrhagia (Correct answer)
- Delayed bleeding after surgery only
- Spontaneous intracranial hemorrhage
Correct answer: Mucocutaneous bleeding such as epistaxis and menorrhagia
Von Willebrand disease impairs platelet adhesion and primary hemostasis, leading to mucocutaneous bleeding; hemarthroses are more typical of hemophilia.
Question 4: Which laboratory test is used to monitor patients on warfarin therapy?
- Activated partial thromboplastin time (aPTT)
- Prothrombin time/INR (PT/INR) (Correct answer)
- Platelet count
- Anti-Xa activity level
Correct answer: Prothrombin time/INR (PT/INR)
Warfarin inhibits vitamin K-dependent factors (II, VII, IX, X), which are measured by the PT/INR; the aPTT monitors heparin therapy.
Question 5: Which combination of laboratory findings is most characteristic of disseminated intravascular coagulation (DIC)?
- Isolated elevation of PT with normal platelet count
- Elevated D-dimer, prolonged PT/aPTT, low fibrinogen, and thrombocytopenia (Correct answer)
- Normal fibrinogen with elevated D-dimer only
- Elevated platelet count with isolated low fibrinogen
Correct answer: Elevated D-dimer, prolonged PT/aPTT, low fibrinogen, and thrombocytopenia
DIC involves simultaneous widespread coagulation and fibrinolysis, consuming clotting factors and platelets, resulting in elevated D-dimer, prolonged PT/aPTT, low fibrinogen, and thrombocytopenia.
Question 6: A patient with antiphospholipid syndrome (APS) is at highest risk for which complication?
- Severe bleeding diathesis due to factor inhibitors
- Arterial and venous thrombosis and recurrent pregnancy loss (Correct answer)
- Aplastic anemia from bone marrow failure
- Autoimmune hemolytic anemia as the primary manifestation
Correct answer: Arterial and venous thrombosis and recurrent pregnancy loss
APS is a thrombophilic condition caused by antiphospholipid antibodies that promote clotting, leading to arterial/venous thrombosis and recurrent pregnancy loss.
Question 7: Which anticoagulant requires NO dose adjustment in patients with severe renal failure?
- Enoxaparin (LMWH)
- Dabigatran
- Warfarin (Correct answer)
- Rivaroxaban
Correct answer: Warfarin
Warfarin is hepatically metabolized and has no significant renal excretion, making it the anticoagulant that does not require dose adjustment in renal failure.
Internal Medicine Exam Hematology 2
A patient has a prolonged PT but normal aPTT.
Deficiency of which coagulation factor is most likely responsible?