Osteocalcin metabolism in late fetal life: fetal and maternal osteocalcin levels.

ABSTRACT

To clarify the osteocalcin metabolism in the fetus, we determined venous osteocalcin levels of 13 women and umbilical arterial and venous osteocalcin levels of their newborns at delivery. Calcium, phosphorus and alkaline phosphatase levels were also established. Umbilical arterial and venous blood calcium and phosphorus levels were significantly higher than maternal venous blood values (P < 0.001 for all). Umbilical arterial calcium was 2.46 +/- 0.02 mmol/l, phosphorus 1.48 +/- 0.04 mmol/l, umbilical venous calcium 2.50 +/- 0.03 mmol/l, phosphorus 1.45 +/- 0.04 mmol/l, maternal calcium 2.16 +/- 0.03 mmol/l, phosphorus 0.98 +/- 0.04 mmol/l. Both umbilical venous (5.85 +/- 0.66 nmol/l) and arterial (3.49 +/- 0.51 nmol/l) osteocalcin levels were significantly higher than maternal values (1.42 +/- 0.15 nmol/l). The high umbilical venous osteocalcin levels may be due to increased osteocalcin degradation in fetus or placental osteocalcin synthesis.