Cocaine-induced microangiopathic hemolytic anemia mimicking idiopathic thrombotic thrombocytopenic purpura: a case report and review of the literature.

Our understanding of the pathogenesis of idiopathic thrombotic thrombocytopenic purpura (TTP) has increased, but remains incomplete, particularly with respect to cases of suspected TTP that are either unresponsive to therapeutic plasma exchange (TPE) or have normal ADAMTS13 (a disintegrin-like and metalloprotease with thrombospondin type 1 motif 13) activity. A 53-year-old woman presented with severe anemia (hemoglobin 1.8 g/dL) and clinical and laboratory findings consistent with TTP in conjunction with acute cocaine use. The patient was treated with TPE until the pre-treatment ADAMTS13 activity was reported as normal without evidence of an inhibitor. TPE was stopped and the patient continued to improve without treatment. This patient's microangiopathic hemolytic anemia (MAHA) appeared to be secondary to cocaine use. The proposed pathogenesis is likely a combination of cocaine-induced vasoconstriction, vascular damage, platelet activation, and procoagulation. This is the fifth published report of cocaine-induced MAHA and to our knowledge the first with ADAMTS13 testing.