Decreased production or increased turnover of antithrombin III in severe acquired coagulopathy

During the course of severe coagulopathy in an infant suffering from septicaemia and shock, antithrombin III levels were determined repeatedly before and during substitution therapy with human antithrombin. By mathematical analysis of these data, using a biexponential function, the plasma elimination half-life of the antithrombin III was estimated to be 7.5–10.5 h. Compared with known plasma half-lives of radioactively labelled antithrombin III in adults the increase was five-to ten-fold. This indicates that the significantly decreased levels of antithrombin III in this case of coagulopathy were at least partly due to an accelerated consumption of antithrombin III. The estimation of the plasma elimination half-life of antithrombin III helps to differentiate decreased production from increased consumption in cases of severe coagulopathy. Thus, a more precise diagnosis of disseminated intravascular coagulation can be made whilst taking advantage of substitution therapy and avoiding the hazards of radioactive tracer proteins.