[Contraceptive agents and antithrombin III. New causes of thrombosis].

In response to an article on the effect of contraceptive agents on antithrombin III the role of other coagulation inhibitors in inducing thrombosis is stressed namely protein C and heparin cofactor II. Deficiency of both protein C and heparin cofactor II leads to deep venous thrombosis. In 10 to 15% of deep venous thrombosis cases deficiency of antithrombin or protein C was the underlying cause according to research data. Congenital protein C deficiency is more frequent than antithrombin deficiency. Protein C levels were measured from 1983 using immunochemical methods and after 1985 using independently designed methods. The results showed deficient conditions in many Norwegian families. As warfarin reduces the blood concentration of protein C low warfarin doses and effective heparin treatment must be assured when patients are treated for protein C deficieny. In conclusion the importance of measurement of blood coagulation inhibitors (antithrombin protein C heparin cofactor II) in those susceptible to deep venous thrombosis is emphasized.