Review Question - QID 104742

This clinical presentation is consistent with thrombotic thrombocytopenic purpura (TTP), which is associated with a pentad of signs and symptoms including fever, microangiopathic hemolytic anemia, thrombocytopenia (with associated petechiae), renal dysfunction, and neurological or mental status changes.

TTP is a rare and severe bleeding disorder caused by strands of fibrin being deposited in multiple small vessels and the presence of hyaline thrombi affecting multiple organs, including the kidneys and brain. It presents with the pentad of symptoms described above. Pertinent laboratory findings include: anemia, thrombocytopenia (with prolonged bleeding time), elevated indirect bilirubin and LDH, negative Coombs' test, and normal PT/INR and PTT. In TTP there is reduced ADAMTS13 activity. This metalloprotease is involved in the cleaving of von Willebrand factor (vWF); when its activity is reduced, unusually large vWF multimers accumulate and cause aggregation and activation of platelets and subsequent thrombi. A helpful mnmenoic for TTP is a FAT Registered Nurse (FAT RN: Fever, Anemia, Thrombocytopenia, Renal dysfunction, and Neurological changes).

Figure A shows petechiae, a result of thrombocytopenia, on the left foot. Figure B shows a peripheral blood smear with schistocytes, which are seen in microangiopathic hemolytic anemias such as TTP.
Illustration A provides a schematic for the diagnostic workup of thrombocytopenia.

Incorrect Answers:
Answer 1: Idiopathic thrombocytopenic purpura would be associated with isolated thrombocytopenia, in the absence of the systemic symptoms and hemolytic anemia observed in this case.
Answer 2: Disseminated intravascular coagulation would be associated with prolonged PT/INR and PTT.
Answer 4: Hemolytic uremic syndrome can present in a similar fashion to TTP but is not associated with fever and neurologic symptoms or mental status changes.
Answer 5: Evan's syndrome is characterized by the combination of idiopathic thrombocytopenic purpura and autoimmune hemolytic anemia, but would be unlikely to present with fever and neurologic symptoms as in this case.