Bone gamma-carboxyglutamic acid containing protein in the perinatal period.

We measured bone gamma-carboxyglutamic acid-containing protein (BGP), calcium (Ca), phosphorus (P), and alkaline phosphatase (Al-P) in paired maternal and cord sera, and urinary gamma-carboxyglutamic acid (gamma-Gla) in neonates. The circulating BGP was 41.21 +/- 2.47 ng/ml and 7.44 +/- 0.87 ng/ml in the cord (n = 15) and the maternal (n = 14) sera, respectively. The urinary gamma-Gla in the neonates was 147.68 +/- 10.75 mumol/g creatinine (n = 15). The cord serum BGP was significantly higher than the normal adult level. The maternal serum BGP was at the same level as in other adults. It is conceivable that the fetus may produce BGP during gestation, as the cord serum BGP level was significantly higher than the maternal level and there was no correlation between the cord and maternal serum BGP concentrations. The reason for the elevated circulating BGP level in the cord serum is not known, but increased bone turnover may be a factor. The cord serum BGP may include not only carboxylated but also non-gamma-carboxylated GP because of fetal vitamin K deficiency.