Prothrombin determination in plasma and in liver biopsies in chronic liver diseases

Following ribosomal synthesis of the protein moiety of prothrombin, postribosomal carboxylation in the liver is necessary to obtain prothrombin ready for physiologic activation. Both decarboxyprothrombin and carboxyprothrombin can be determined by means of specific activators. Using synthetic substrates for thrombin, a micro-prothrombin assay suitable for functional determinations of decarboxy- and carboxy-prothrombin in liver biopsies was evolved. Decarboxyprothrombin was not found in plasma, independent of the kind of liver disease. Prothrombin determination in 31 liver samples showed no relation between the absolute concentration of carboxyprothrombin and decarboxyprothrombin and the kind of disease. The carboxyprothrombin fraction of total prothrombin was correlated with the activity of histologically estimated fibrosis in the liver.