Concentration of Prothrombin in Blood of Babies (3 to 7 Days Old)

Abstract

The ease with which nutritional deficiency states develop in young infants suggests the advisability of studying their prothrombin level, since it is now known that vitamin K is required for the synthesis of this clotting factor.Blood was obtained by venipuncture from normal healthy infants varying in age from 3 to 7 days. The prothrombin was quantitatively determined by the senior author's method1 on both the undiluted plasma and on plasma diluted with an equal volume of saline solution. Typical cases of this series are presented in Table I.The results plainly show that the prothrombin concentration in the blood of the babies studied was essentially the same as that of normal adult blood. It was found, however, that the prothrombin diminished in infants' blood more rapidly than from that of adults, and curiously in a few bloods, such as Case 3, the decrease of prothrombin was strikingly rapid when the plasma was diluted.These findings are completely at variance with those reported by Brinkhous, Smith and...