[Latent vitamin K deficiency in breast-fed infants].

Quick test, coagulation activity of vitamin K-dependent clotting factors, factor II activity by ecarin, levels of factor II immunoreactive antigen and acarboxyprothrombin were examined in two groups of infants, breast-fed and bottle-fed at the ages of one month and 3 months. None of them received vitamin K at birth and later. Acarboxyprothrombin could be demonstrated in about 14% at the both age of life of breast-fed children, but not in the groups of bottle-fed infants. The activity of coagulation factors was significantly lower in the acarboxyprothrombin-positive group compared to the acarboxyprothrombin-negative group. In none of the infants manifest bleeding was observed. No difference in the activities of factors could be detected in the acarboxyprothrombin-negative groups of breast- and bottle-fed children. These data suggest a frequent latent deficiency of vitamin K in breast-fed infants.