Hypocalcemia in infants of diabetic mothers. Studies in circulating calciotropic hormone concentrations.

Twenty-two infants of diabetic mothers (IDM) were studied and were divided into two groups: a first group of 14 IDM did not receive vitamin D3 and was studied at birth and at 2, 24, 48 and 120 hours; a second group was given daily dosage of 60 microgram of vitamin D3 from 3 hours to 120 hours and was studied at 2 hours and 120 hours. In the first group, serum calcium levels decreased markedly during the first 24 hours of life (mean +/- SD: 1.77 +/- 0.3 mmol/l, p less than 0.01) and remained low at 5 days. Serum phosphorus levels remained normal but serum magnesium levels decreased significantly at 24 hours (mean +/- SD: 0.64 +/- 0.108 mmol/l, p less than 0.01) and returned to normal at 5 days. Serum immunoreactive parathormone levels increased consistently to high levels at 24 hours and remained elevated at 120 hours (p less than 0.001). Serum immunoreactive calcitonin levels increased at 24 hours (p less than 0.001) and decreased at 120 hours to low or undetectable values in all infants. In group II, serum 25O-HD levels and 1.25 OH2 D levels increased significantly (p less than 0.001) respectively to 27.2 +/- 2.7 ng/ml and 114 +/- 20 pg/ml at 5 days. The results of this study show hypocalcemia to be a common event in IDM during the first days of life and furthermore hypophosphatemia, hypoparathyroidism, hypomagnesemia or defect of vitamin D metabolism would not seem to be the main etiological factors.