Differentiating malignant hypertension-induced thrombotic microangiopathy from thrombotic thrombocytopenic purpura

Abstract

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.

A case of malignant hypertension with thrombotic microangiopathy

“…While 56% of patients undergo dialysis after onset, 24% of patients become dialysis-independent. 3,5 In this case, the patient's blood pressure, renal function and anaemia significantly improved after antihypertensive treatment. Careful differentiation between MHT-induced TMA and HUS/TTP is crucial.…”

“…Although plasma exchange can be initiated while any alternative cause is carefully screened, it is important to differentiate HUS/TTP from MHT‐induced TMA because the treatments and prognosis are different. To the best of our knowledge, there are no more than 19 MHT‐induced TMA with detailed information reported in the literature . Prior history of hypertension, high mean arterial pressure, significant renal impairment but relatively modest thrombocytopenia and lack of ADAMTS‐13 deficiency (activity <10%) at diagnosis are clues to diagnose MHT‐induced TMA .…”

“…Patients with MHT respond well to antihypertensive treatment and have favourable non‐renal outcomes. While 56% of patients undergo dialysis after onset, 24% of patients become dialysis‐independent …”

“…3 Prior history of hypertension, high mean arterial pressure, significant renal impairment but relatively modest thrombocytopenia and lack of ADAMTS-13 deficiency (activity <10%) at diagnosis are clues to diagnose MHT-induced TMA. 3 Although MHT can involve reduced ADAMTS-13 activity, the level is usually more than 50%. 4 Plt count <50 × 10 9 /L has been considered as a criterion to initiate plasmapheresis.…”

Malignant Hypertension with Thrombotic Microangiopathy

“…Additionally, the cause of TMA was malignant hypertension according to the presence of hypertensive retinopathy and PRES, which enabled us to avoid unnecessary plasma exchange. A past history of hypertension, high mean arterial pressure, and significant renal impairment, but relatively modest thrombocytopenia, can also be clues for diagnosing malignant hypertension-induced TMA, according to a recent study (8).…”