Absorption, dosage, and effect on mineral homeostasis of 25-hydroxycholecalciferol in premature infants: Comparison with 400 and 800 IU vitamin D-2 supplementation

Extract: Because the efficiency of vitamin D absorption or hepatic uptake and 25-hydroxylation appears decreased in very premature infants the routine use of 25-hydroxycholecalciferol (25-OHD-3) supplementation has been suggested. Absorption studies of a 3 microgram per kilogram orally administered dose of 25-OHD-3 showed peak serum 25-hydroxyvitamin D-2 and -vitamin D-3 (25-OHD) concentrations at 4 to 8 hours similar in timing but of lesser magnitude to those seen in adults. Administration of 1 microgram per-kilogram birth weight/day of 25-OHD-3 corrected moderately low, but not very low serum (25-OHD) concentrations, and 2 microgram per kilogram BW/day resulted in rapid and sustained increases in serum 25-OHD. Administration of 800 IU ergocalciferol (D-2) also produced significantly higher serum 25-OHD concentrations than those in infants given 400 IU vitamin D-2, but increases in serum 25-OHD were more gradual than in infants given 25-OHD-3. In treatment trials with infants weighing less than 1500 gm, those given 800 IU D-2, compared with those given 400 IU D-2, had higher serum calcium concentrations and less frequent moderate or severe hypomineralization. Infants given 2 micrograms per kilogram BW 25-OHD-3 had a significant increase in serum phosphorus values, but a decrease in serum calcium and magnesium concentrations and parathyroid hormone was also supressed to low normal values. The frequency of moderate or severe hypomineralizaton remained the same as in infants given 400 IU D-2. In a subgroup of infants, serum 1,25-dihydroxyvitamin D was elevated over adult values, both in infants given 25-OHD-3 and in infants given vitamin D-2. Serum vitamin D concentrations were undetectable in four of six infants receiving vitamin D-2. Although 800 to 1000 IU D-2 can be recommended as routine vitamin D supplementation in very premature infants fed standard formula, the use of 25-OHD-3 requires further study. (Author)