Immunoreactive calcitonin in the mother, neonate, child and adult.

Immunoreactive calcitonin (iCT) was measured in umbilical arterial and venous blood and in maternal peripheral blood in 32 normal deliveries. The results were compared with values found in nonpregnant adult females. The umbilical arterial blood contained significantly higher concentrations of iCT than umbilical venous blood (p less than 0.001). The serum iCT in maternal peripheral blood was significantly higher than in normal nonpregnant subjects (p less than 0.001). Serum iCT was also measured in 342 male and female subjects ranging in age from 1 hour to 60 years. Serum iCT was found to be high early in life and to diminish with age. Our data suggest that calcitonin may be of physiologic significance in bone formation during intrauterine life and childhood. High serum iCT may also be responsible for the hypocalcemia seen in the neonatal period.