Nephrotic syndrome with renal vein thrombosis: pathogenetic importance of a plasmin inhibitor (alpha 2-antiplasmin).

Tests of fibrinolysis were measured by fibrin plate methods in 44 patients with nephrotic syndrome, in 14 of whom renal vein thrombosis was demonstrated. In both groups the level of total fibrinolytic activity was normal, that of vascular plasminogen activator was decreased, and that of an inhibitor of plasminogen activation was elevated. The level of a plasmin inhibitor, measured by the fibrin plate method, was elevated in 13 of 14 patients with, but only in 12 of 30 without, renal vein thrombosis (p less than 0.005). The plasmin inhibitor was identical with alpha 2-antiplasmin. The data suggest that an increased level of alpha 2-antiplasmin may be a factor in determining susceptibility to the development and persistence of renal vein thrombosis in patients with nephrotic syndrome.