Hypercalcitoninemia in infancy.

Immunoreactive calcitonin (iCT) was measured in 19 infants with neonatal hypocalcemia. The infants had a variety of neonatal diseases and stresses. iCT levels were generally elevated to two to 20 times the adult values. Poor correlation existed between the infant age and the level of iCT or between iCT alone and the serum calcium. However, there was significant correlation between the serum calcium and the ratio of the iCT to infant age from conception, suggesting that both infant age and iCT levels in combination may be related to hypocalcemia. Also, it appears that a variety of neonatal stresses may be associated with increased sensitivity to the hypocalcemic effect of iCT, as well as increased levels of iCT.