Differentiating malignant hypertension-induced thrombotic microangiopathy from thrombotic thrombocytopenic purpura.

OBJECTIVES: Malignant hypertension can cause thrombotic microangiopathy (TMA) and the overall presentation may mimic thrombotic thrombocytopenic purpura (TTP). This presents a dilemma of whether or not to initiate plasma exchange. The objective of the study was to determine the clinical and laboratory manifestations of malignant hypertension-induced TMA, and its outcomes.

METHODS: Using several search terms, we reviewed English language articles on malignant hypertension-induced TMA, indexed in MEDLINE by 31 December 2013. We also report a new case. All these cases were analyzed using descriptive statistics.

RESULTS: A total of 19 patients, with 10 males, had a median age of 38 years at diagnosis; 58% had a history of hypertension. Mean arterial pressure at presentation was 159 mmHg (range 123-190 mmHg). All had prominent renal dysfunction (mean creatinine of 5.2 mg/dl, range 1.7-13 mg/dl) but relatively modest thrombocytopenia (mean platelet count of 60 × 103/µl, range 12-131 × 10(3)/µl). Reported cases (n = 9) mostly had preserved ADAMTS-13 activity (mean 64%, range 18-96%). Following blood pressure control, the majority had improvement in presenting symptoms (100%) and platelet counts (84%); however, only 58% had significant improvement in creatinine. More than half (53%) needed hemodialysis. One patient died of cardiac arrest during pacemaker insertion.

CONCLUSION: Prior history of hypertension, high mean arterial pressure, significant renal impairment but relatively modest thrombocytopenia and lack of severe ADAMTS-13 deficiency (activity <10%) at diagnosis are clues to diagnose malignant hypertension-induced TMA. Patients with malignant hypertension respond well to antihypertensive agents and have favorable nonrenal outcomes.