[Concentrations of calcium and bone remodeling biomarkers in umbilical cord blood and urine of newborn infants during delivery].

OBJECTIVE

To evaluate calcium, phosphorus, parathormone (PTH), osteocalcin, and alkaline phosphatase concentrations in cord blood, pyridinoline concentrations in urine, and the pyridinoline/creatinine ratio in order to indirectly assess late bone remodeling in the newborn by comparing concentrations of these substances with those in the mother during the third trimester and delivery.

PATIENTS AND METHODS

Calcium, phosphorus, PTH, osteocalcin, and alkaline phosphatase levels in cord blood, pyridinolines in urine and the pyridinoline/creatinine ratio were evaluated in 38 healthy pregnant women during the last two months of pregnancy and during delivery. To determine concentrations of these substances, samples from vein umbilical cord blood were obtained immediately after birth and urine samples were obtained from the neonates within 24 hours of delivery.

RESULTS

The mean calcium concentration in cord blood was higher than maternal values during delivery. Concentrations of PTH in cord blood were much lower than those in maternal blood during pregnancy, alkaline phosphatase levels were similar, and osteocalcin levels were higher. Mean urine pyridinoline concentrations in the neonates were much higher than those in the mother during the third trimester and delivery.

CONCLUSION

During delivery newborn infants are hypercalcemic compared with their mothers, presenting a state of relative hypoparathyroidism. Concentrations of remodeling biomarkers are higher in the newborn than in the mother, revealing a higher rate of bone turnover in the fetus.