Vitamin D requirement in infants receiving parenteral nutrition.

The adequacy of low dose vitamin D (25 IU/dl) parenteral nutrition (PN) solution was studied in 18 infants. All infants had surgical indications for PN. The birth weights were 2810 +/- 135 g and gestational ages 37.4 +/- 0.5 wk (mean +/- SEM). Duration of study ranged from 5 to 175 days. Thirteen infants were studied for up to 6 weeks and five infants for 71 to 175 days. Results showed that studied infants maintained growth along normal percentiles for weight, length, and head circumference. Vitamin D status as indicated by serum 25 hydroxyvitamin D (25 OHD) rose from 15 +/- 1.9 ng/ml to 26 +/- 2.8 ng/ml, mean +/- SEM (p less than 0.001) after 9 days, and remained normal up to 6 months. Five infants with biochemical liver dysfunction also had normal serum 25 OHD concentrations, indicating the hepatic 25 hydroxylation process was not severely impaired. Serum total and ionized calcium, phosphorus, and vitamin D-binding protein concentrations were normal. Serum magnesium was mildly elevated in five infants (2.6 to 3 mg/dl) on one occasion and resolved spontaneously. Serum alkaline phosphatase (AP) concentrations rose above baseline values in 12 of 17 infants, but remained within normal range (less than 400 IU/liter at 30 degrees C). Another infant with markedly elevated AP values died from liver dysfunction. Radiographs of the forearms were normal except for marked demineralization in one infant in spite of normal 25 OHD concentrations. We conclude that 25 IU vitamin D/dl of nutrient infusate is adequate to maintain normal vitamin D status, as indicated by normal serum 25 OHD concentrations in infants receiving PN for as long as 6 months.