Parathyroid hormone and neonatal calcium homeostasis: evidence for secondary hyperparathyroidism in the Asian neonate.

Calcium, 25-hydroxyvitamin D (25 OHD), and parathyroid hormone (PTH) concentrations were measured in 11 Asian and ten Caucasian pregnant women at parturition and in their respective newborns following a full term normal delivery. Maternal calcium and 25 OHD concentrations were significantly lower while PTH concentrations were significantly greater in Asians than those in Caucasians. There was a significant inverse relationship between calcium and PTH and the relationship between 25 OHD and PTH concentrations. Neonatal calcium and 25 OHD concentrations were also significantly lower and PTH concentrations significantly higher in Asians than those in Caucasians. There was a highly significant inverse correlation between neonatal calcium and PTH concentrations. Three of the 11 Asian babies had supranormal concentrations of PTH in their cord blood. We conclude that PTH participates in neonatal calcium homeostasis and Asian newborns have frequent secondary hyperparathyroidism.