Renal thrombotic microangiopathies induced by severe hypertension

Renal thrombotic microangiopathy (TMA) is an uncommon vascular complication of severe hypertension. Until now, its clinical-pathological characteristics and renal survival have been unclear. Twenty-one patients with biopsy-proven renal TMA and with severe or malignant hypertension were retrospectively studied. All the patients exhibited severe hypertension, with systolic blood pressure at 200-280 mmHg and diastolic pressure at 110-180 mmHg. No patients had hemorrhagic manifestations. Elevated lactate dehydrogenase and thrombocytopenia were found in 6 and 5 patients, respectively. Significant proteinuria (>3 g/day) was present in 2 patients and microscopic hematuria in 18 patients. All patients presented with renal insufficiency (creatinine 3.1+/-2.1 mg/dL). The level of von Willebrand factor:antigen (vWF:Ag) in patients was not significantly higher than that in the healthy subjects, while the ADAMTS13 (a disintegrin and metalloprotease, with thrombospondin-1-like domains) activity was not significantly lower than that in the healthy subjects. Renal histology showed a TMA involving preglomerular arterioles and/or interlobular arteries characterized by fibrin deposits and vascular wall sclerosis. Fibrin glomerular microthrombi were not observed in these patients. Four patients required hemodialysis upon admission for severe acute renal failure. On follow-up, 3 patients had recovered normal renal function and 14 had mild renal insufficiency (creatinine 1.8+/-0.3 mg/dL), while 4 patients still required persistent hemodialysis. In conclusion, compared with patients having hemolytic uremic syndrome/thrombocytopenic purpura, our patients showed a low incidence of thrombocytopenia and better renal outcome.