HY USMLE Q #1056 – Hematology

A 23-year-old man comes to the physician for a follow-up examination. Laboratory studies show:

Hemoglobin                                                                       16 g/dL
Bleeding time                                                                    6 minutes
Prothrombin time                                                           14 seconds
Partial thromboplastin time                                     45 seconds

Which of the following is the most likely explanation for these findings?

  Antibodies against ADAMTS13
  Deficiency of von Willebrand factor
  Impaired platelet aggregation
  Inhibitor of factor VIII
  Vitamin K deficiency