Disorders of Coagulation

A 17-year-old male presents to an urgent care clinic complaining of swelling and pain in his left knee after a fall from a bicycle. He has a history of recurrent swelling and pain in multiple joints as well as prolonged bleeding after mild trauma throughout his lifetime. Laboratory studies demonstrate platelet of 240 k/mu L (reference range: 150-440 K/mu L), a prothrombin time (PT) of 13.5 seconds (reference range: 11.8-15 seconds), and a partial thromboplastin time (PTT) of 48 seconds (reference range: 23.6-36.4 seconds). Fibrinogen and thrombin time are found to be normal.