Thrombosis in patients with paroxysmal nocturnal hemoglobinuria.

Paroxysmal nocturnal hemoglobinuria is a disorder associated with hemolysis, pancytopenia, and thrombosis due to the loss of the glycosylphosphatidylinositol (GPI) anchored complement regulatory proteins. The mechanism of thrombosis is multifactorial. Although intravascular hemolysis has been implicated as the etiology, the effect of complement on GPI anchor-deficient platelets, granulocytes, monocytes, and endothelial cells contributes significantly to the risk of thrombosis. Moreover, there appears to be an underlying inflammatory state that is linked to hemostatic activation that may induce thrombosis through a pathway independent of hemolysis.