Q: 22 year old male in ICU is admitted for unrelated reason, continue to show prolonged PTT but normal PT, Bleeding Time and Platelet count. Which disease process only prolonges PTT but all other normal basic coagulation profile?
Answer: Factor X11 deficiency
Factor X11 deficiency is also known as Hageman factor deficiency. It is very rare with evidence of about 1 in 1 million. Fortunately its a benign process, does not cause bleeding and normally do not need treatment. Even with major surgery, bleeding manifestations are extremely rare. Usually, it is diagnosed accidently by a prolonged activated partial thromboplastin time (aPTT) test.