Minimal heparin cofactor activity in disseminated intravascular coagulation and cirrhosis.

An assay technic for measuring heparin cofactor activity in which antithrombin activity can be assessed without plasma attenuation even in the presence of therapeutic levels of heparin is presented. Heparin-activated anti-thrombin activity was markedly depressed in plasmas of four patients with disseminated intravascular coagulation and in ten patients with cirrhosis. Residual activity in those plasmas appeared qualitatively normal, and no inhibitor (platelet factor IV activity) was observed. Plasmas from patients with disseminated intravascular coagulation and cirrhosis required more heparin to obtain in vitro clotting time prolongation equivalent to normal.