Medical Emergencies · single question
Which laboratory test is most useful for evaluating hemophilia A?
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Correct answer: A. Activated partial thromboplastin time (aPTT/PTT)
Hemophilia A is an intrinsic-pathway clotting factor (VIII) deficiency, which prolongs the aPTT (PTT). Specific factor VIII assays confirm the diagnosis.Other options: PT assesses the extrinsic pathway; bleeding time and platelet count assess platelet function/number, which are normal in hemophilia.Key exam takeaway: Hemophilia A = prolonged aPTT (intrinsic pathway); confirm with factor VIII assay.
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