Turnover of radiolabelled plasminogen and prothrombin in cirrhosis of the liver.

The turnover of purified radiolabelled plasminogen was studied in four patients with cirrhosis of the liver, and that of radiolabelled prothrombin in six patients with cirrhosis of the liver. The cirrhotic patients showed an increased fractional catabolic rate and a decreased synthetic rate, resulting in subnormal plasma levels of plasminogen and prothrombin. The plasma concentration of the two proteins correlated with the synthetic rate, but not with the fractional catabolic rate. Heparin infusion prolonged the shortened half-life of plasminogen in two cirrhotics from 1.25 to 2.10 days and from 1.45 to 1.90 days, and the half-life of prothrombin in three cirrhotics from 2.25 to 2.70 days, from 2.35 to 2.80 days and from 2.40 to 3.70 days. These results indicate that the abnormal turnover of labelled plasminogen and prothrombin in cirrhosis of the liver is due to two mechanisms; increased breakdown, reversible by heparin administration, and impaired synthesis. The decreased plasma levels are, however, mainly caused by decreased synthesis.