Malignant arterial hypertension is a life-threatening condition accompanied by acute renal failure, which in most cases results in irreversible loss of renal function. The morphological substrate of the disease is often thrombotic microangiopathy the mechanism of which in malignant hypertension is not fully understood. The article presents clinical observations of patients with malignant hypertension and renal dysfunction who had renal biopsy-proven thrombotic microangiopathy. The characteristic feature of both observations is the lack of specific hematologic signs of thrombotic microangiopathy syndrome, which creates diagnostic difficulties. Factors attributed to the lack of microangiopathic hemolysis and thrombocytopenia are described. Potential mechanisms of developing thrombotic microangiopathy in malignant hypertension are
discussed.

Keywords: acute renal injury, renal insufficiency, malignant hypertension, thrombotic microangiopathy