Differences in reactivity to vitamin K administration of the vitamin K-dependent procoagulant factors, protein C and S, and osteocalcin.

Vitamin K is a trace nutrient necessary not only for the synthesis of four plasma clotting factors but also the production of two important anticlotting factors, protein C and protein S, and the synthesis of two bone proteins. If protein C and protein S are produced more quickly and/or in higher quantities than four plasma coagulation factors after vitamin K administration, then the result is unfavorable for stopping of hemorrhage. We therefore studied the difference of time dependence of prothrombin procoagulant factors, protein C and S and bone Gla protein after the administration of vitamin K in normal and vitamin K-deficient neonates. Results of our study showed that, on the whole, coagulation factors increased markedly more than anticlotting factors after vitamin K administration. Furthermore, the increase in bone Gla protein was also higher compared with protein C activity, although the detailed mechanism of the difference in reactivity of prothrombin procoagulant factors, protein C and S and bone Gla protein to vitamin K administration is not clear.