Early oral administration of vitamin D and its metabolites in premature neonates. Effect on mineral homeostasis.

For five days, three groups of six premature infants each were fed human milk and given a daily dosage of one of the following: vitamin D3 (30 micrograms), 25-OH D3 (10 micrograms) and 1,25-OH D3 (0.5 micrograms). The infants in the groups were matched for gestational age and birthweight. Administration of 25-OH De or 1,25-(OH)2 D3 did not significantly modify the course of early neonatal hypocalcemia as compared with infants receiving vitamin C3. Mean plasma Ca +/- S. D. (mg/100 ml) decreased to nadir values at 48 hr (D3: 5.7 +/-1.2; 25 OH D3: 6.8 +/- 0.9; 1.25-(OH)2 D3: 6.7 +/-1.1). A progressive increase toward normal values was seen at 120 and 168 hr in the three groups. Mean plasma immunoreactive parathyroid hormone +/- S.D. (microliters Eq/ml) followed an opposite pattern with peak values at 48 hr (D3: 231 +/- 137; 25-OH D3: 281 +/- 138; 1,25-(OH)2 D3:211 +/- 149). Mean plasma +/- S.D. 25-OH values (ng/ml) were low at 1.2 hr (8.7 +/- 4.8) n: 16) and increased significantly after 7 days of D3 (18.2 +/- 4.2 P less than 0.001) and 25-OH D3 administration (46 +/- 10.3 P less than 0.001)/Mean plasma iCT +/- S.D. (pg/ml) reached peak values at 24 hr (D3: 457 +/- 186; 25-OH D3: 415 +/- 121; 1.25-(OH)2 D3: 443 +/- 183). These data suggest that the various forms of vitamin D are well absorbed in preterm infants and that administration of vitamin D metabolites during the first days of life is not warranted for they prophylaxis of early neonatal hypocalcemia.