Heparin-like inhibitor of blood coagulation in normal newborn

Abstract

THE level of the blood coagulation factors in the newborn is known to be markedly lower than that in the adult. Generally this is attributed to a lack of synthetic capacity of the liver and a deficiency in vitamin K. We describe here a re-investigation of this problem making use of recently developed methods that determine both the coagulation factors and the abnormal proteins induced by vitamin K absence (PIVKAs). We found low coagulation factor activity in the newborn but no evidence for vitamin K deficiency. In more than half the samples a hitherto unrecognised inhibitor of blood coagulation could be demonstrated. At 3 d of age this inhibitor was found in all babies investigated. On the basis of its properties in blood coagulation tests the inhibitor could not be distinguished from heparin.