Renal abnormalities reverted by plasma exchange in thrombotic thrombocytopenic purpura.

Thrombotic thrombocytopenic purpura (TTP) is usually accompanied by renal disfunction presumable due to diffuse thrombotic occlusions in the microcirculation. Two patients with TTP and slight renal failure with proteinuria and microscopic hematuria, were treated by repeated plasma exchanges with fresh frozen plasma, associated with prednisone and cyclophosphamide in one case, and prednisone alone in the other one. Platelet count, hematocrit and lactic dehydrogenase reverted to normal values within the fourth exchange; circulating immune complexes were never detected. Plasma factor stimulating prostacyclin activity lacked in only one patient and returned to normal levels after plasma exchange without being affected during a hematologic relapse. Renal function and urinary abnormalities reverted to normal by the end of plasma exchange and nine and six months renal and hematologic follow-up is still negative. Renal abnormalities in TTP seem to take advantage of early treatment by plasma exchange, which further to replacement of missing plasma factors, can account for the removal of toxic substances to be further investigated on.