Medical Emergencies · single question
Which laboratory test should be performed to assess a hemophiliac patient's clotting ability?
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Correct answer: C. PTT (Partial Thromboplastin Time)
- A. CBC measures blood cell counts including platelets but does not assess clotting factor activity. Hemophilia involves factor deficiency — platelets are typically normal.
- B. INR/PT evaluates the extrinsic pathway (Factor VII) and is NORMAL in hemophilia. INR is used to monitor warfarin therapy.
- C. The PTT (aPTT) evaluates the INTRINSIC coagulation pathway, involving Factors VIII (hemophilia A) and IX (hemophilia B). Hemophiliacs have a prolonged PTT. PT/INR evaluates the extrinsic pathway (Factor VII) and is NORMAL in hemophilia.
- D. PT tests the extrinsic pathway and is normal in hemophilia. The intrinsic pathway test (PTT/aPTT) is correct.
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