Approach to bleeding disorders (platelet dysfunction) Quiz: Ace Your Exams

A 24-year-old woman presents to the clinic with complaints of easy bruising and frequent nosebleeds over the past several months, and she reports progressively worsening heavy menstrual periods. Her mother and maternal uncle have a history of spontaneous bleeding. She has no significant past medical history and takes no prescribed medications. She has been taking glucosamine supplements for joint pain from running and doesn't take any other supplements or medications. Vital signs are within normal limits. Physical examination reveals scattered ecchymoses over the bilateral upper extremities. There is no hepatosplenomegaly. Laboratory results are shown below. Which of the following is the most likely cause of this patient’s bleeding?

Laboratory Test	Result	Reference Range
Hemoglobin	11.8 g/dL	12-16 g/dL
White blood cell count	7,500 /µL	4,500-11,000 /µL
Platelets	140,000 /µL	150,000-400,000 /µL
Peripheral smear	No schistocytes	No schistocytes
Prothrombin time (PT)	12 seconds	11-15 seconds
Activated partial thromboplastin time (aPTT)	42 seconds	25-40 seconds
Fibrinogen	250 mg/dL	200-400 mg/dL
D-dimer	0.5 mg/L	<0.5 mg/L
Creatinine	1.0 mg/dL	0.6-1.2 mg/dL