Parathormone and calcitonin in the pathogenesis of neonatal hypocalcemia

Abstract

Hypocalcemia (HOC) is common in infants of diabetic mothers (IDM), premature newborns (NB), and asphyxiated infants. In addition, it is more frequent in boys than in girls. To investigate the cause of HOC, we have measured serum calcium, RIA-parathormone (PTH), and calcitonin (CT) in IDM, premature, and asphyxiated NB during the first week of life. These subjects were compared to healthy term infants as well as a group of neonates with documented HOC (Ca ≤ 7.5 mg/dl). Mean PTH and CT concentrations were similar in both sexes and in vaginal (n=188) and cesarean section deliveries (124), and there was no difference between small (18), appropriate (144), and large (42) for date term NB. Serum PTH in premature NB, however, was significantly lower (p<0.05) and CT concentrations were higher (p<0.01) than in term NB. IDM had low PTH levels (p<0.05), but CT concentrations were not different from controls. Asphyxiated infants had both, elevated PTH and CT levels (p<0.01). Mean PTH concentrations in hypocalcemic NB were not different from controls, but CT levels were higher than in any other infant group (p<0.001). These data suggest that hypercalcitoninemia and hypoparathyroidism alone may cause HOC, but that the risk of HOC is particularly high in infants with combined hypoparathyroidism and hypercalcitoninemia.