Serum 1,25-dihydroxyvitamin D concentrations in premature infants: Preliminary results

Serum 1,25(OH)2D concentrations were measured in serial serum samples from 19 premature infants of 29.6±1.3 weeks gestation and 1,129±159 g birthweight. 1,25(OH)2D was always normal or elevated and mean concentrations increased with age (adult, 55.2±13; infants, 1–2 weeks, 81.5±37.7 pg/mg; 3 weeks, 65±21; 6 weeks, 90.0±17.3; 9 weeks, 99.0±25.1; 12 weeks, 103.3±26.6 pg/ml). No correlation was seen with 25-OHD. Infants given 800 IU D2 supplements had lower 1,25(OH)2D levels than infants given 400 IU D2. Breast fed infants had initially higher 1,25(OH)2D levels; however, this was not sustained. These preliminary data suggest that premature infants regulate 1,25(OH)2D production similar to more mature infants and children. Whether the premature infant has a normal gastrointestinal and/or bone responsiveness to 1,25(OH)2D and whether these elevated 1,25(OH)2D concentrations are “adequately elevated” requires further study.