Perinatal primate parathyroid hormone metabolism.

Near-term fetal and neonatal parathyroid gland function has been studied in the Rhesus monkey. Fetal serum ionized calcium (Ca++) levels are significantly greater than simultaneously obtained maternal levels. Fetal serum parathyroid hormone (PTH) was undetectable both in the basal state and in association with EDTA-induced fetal hypocalcemia. Induced maternal hypocalcemia was associated with increased maternal serum PTH levels and no change in fetal basal serum Ca++ or PTH levels. Only a minimal decrease in simian neonatal serum Ca++ occurred over the first 48 h of life. Normal adult levels of serum PTH were present as early as 6 h of neonatal life. Induced hypocalcemia at 12 h of age resulted in a significant increase in serum PTH levels.