Vitamin D and mineral metabolism in the very low birth weight infant receiving 400 IU of vitamin D.
OBJECTIVE
To examine (1) the effect of vitamin D intake (380 to 480 IU daily) on plasma 25-hydroxyvitamin D (25-OHD) and 1,25-dihydroxyvitamin D (1,25-(OH)2D) concentrations and (2) the relationship of 1,25-(OH)2D to calcium and phosphorus absorption and retention in the very low birth weight infant receiving a preterm infant formula.


METHODS
Eleven "well" infants with a birth weight and gestational age (mean +/- SD) of 1078 +/- 128 gm and 29 +/- 1.9 weeks, respectively, were studied for a 3-week period. Weight and postnatal age (mean +/- SD) at the beginning of the study were 1132 +/- 56 gm and 16 +/- 6 days, respectively. All infants were fed a preterm infant formula and tolerated a full enteral intake (120 kcal/kg/day) for the duration of the study.


METHODS
Plasma 25-OHD and 1,25-(OH)2D concentrations were measured at the beginning of the study and at the beginning of each 48-hour balance period. Calcium and phosphorus balance studies (n = 33) were performed weekly.


RESULTS
Plasma 25-OHD (30 +/- 10 ng/ml) and 1,25-(OH)2D (54 +/- 14 pg/ml) concentrations were normal at the beginning of the study. Plasma 25-OHD values did not change, but 1,25-(OH)2D values increased (p less than 0.001) throughout the study. Plasma 1,25-(OH)2D concentrations were not related to calcium or phosphorus absorption and retention, but were a linear function of postconceptional age.


CONCLUSIONS
Normal vitamin D status and activity are maintained in the very low birth weight infant fed a high calcium formula (380 to 480 IU of vitamin D daily). Plasma 1,25-(OH)2D concentrations are not related to calcium absorption but are linearly related to maturity.
Cooke
R
R
Department of Pediatrics, University of Tennessee, Memphis.
Hollis
B
B
Conner
C
C
Watson
D
D
Werkman
S
S
Chesney
R
R
D002118:Calcium / Q000378:metabolism*; D004100:Dihydroxycholecalciferols / Q000097:blood*; D006801:Humans; D006887:Hydroxycholecalciferols / Q000097:blood*; D007230:Infant, Low Birth Weight / Q000378:metabolism*; D007231:Infant, Newborn; D009751:Nutritional Requirements; D010758:Phosphorus / Q000378:metabolism*; D014807:Vitamin D / Q000008:administration & dosage*
D004100:Dihydroxycholecalciferols; D006887:Hydroxycholecalciferols; D014807:Vitamin D; D010758:Phosphorus; D002118:Calcium