Coagulation Disorders USMLE Step 1 Practice Question
A 28-year-old woman presents to the hematology clinic for evaluation of recurrent thromboembolism. She has a history of two unprovoked deep vein thromboses at ages 24 and 26, and two consecutive first-trimester miscarriages. Physical examination is unremarkable. Laboratory studies show: PT: 12 seconds (normal: 11-13.5)
aPTT: 38 seconds (normal: 25-35)
aPTT after mixing with normal plasma: 36 seconds
Lupus anticoagulant: Positive
Anticardiolipin IgG antibodies: 45 GPL units (elevated; normal <15)
Anti-β2 glycoprotein I antibodies: Negative
Protein C activity: Normal
Factor V Leiden mutation: Negative
Prothrombin G20210A mutation: Negative Which of the following is the most likely diagnosis?
Answer choices
- AProtein C deficiency
- BFactor V Leiden heterozygosity
- CProthrombin G20210A mutation
- DIsolated systemic lupus erythematosus without antiphospholipid antibodies
- EAntiphospholipid syndromeCorrect answer
- FDisseminated intravascular coagulation
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