A patient with a diagnosis of thrombotic thrombocytopenic purpura (TTP) is likely to have which of the following laboratory findings?

A Elevated fibrinogen levels
B Prolonged prothrombin time
C Low levels of ADAMTS13 enzyme activity ✓
D Increased platelet count

Explanation

TTP is characterized by a deficiency in ADAMTS13 enzyme activity, which leads to the accumulation of ultra-large von Willebrand factor multimers and subsequent thrombotic microangiopathy.

Source

Harrison's Principles of Internal Medicine
Hematology Hematology: Coagulation Disorders Hematology: Coagulation Disorders Hard MEDICAL Confidence: high