FUNCTIONAL HYPOPARATHYROIDISM IN NEONATAL HYPOCALCEMIA OF INFANT OF DIABETIC MOTHER

Abstract

In neonatal hypocalcemia of infants of diabetic mothers (IDM), there is associated hyperphosphatemia and calcemic responsiveness to parathyroid extract, consistent with possible hypoparathyroidism. The serum immuno-reactive parathyroid hormone (PTH) levels of 28 IDM (15 class A; 13 B,C,D) were studied serially in the first 3 days of life to determine the PTH responses to changes in serum Ca. In class A IDM serum Ca fell from 10.35 mg% at birth to 7.84 at 24-48 hours and rose to 8.86 at 72 hours. In class B,C,D IDM the corresponding values were 9.6, 6.5 and 7.1. Serum ionized Ca fell in all IDM (4.2 to 2.5 to 3.2 mg%), serum Mg was unchanged, and serum P rose (6.1 to 7.0 to 8.3 mg%). Changes in serum PTH were not correlated with changes in serum Ca from birth to 24-48 hours(r-0.09). In class A IDM at 24-48 hours serum PTH was 134±14% of cord PTH values (paired t, p-0.06) and at 72 hours was 124±13%. In class B,C,D IDM, in spite of significant falls in serum Ca, PTH was correspondingly 118±16% (not signifleant)and 105±12%. Serum Ca at 72 hours was positively correlated(r-0.67, p-0.05) and serum P negatively correlated (r-−0.75, p<0.05) with PTH responsiveness at 24-48 hours. The present data are consistent with the thesis that functional hypoparathyroidism is a pathogenetic mechanism for neonatal hypocalcemia in infants of diabetic mothers.