Serial Serum 25-Hydroxyvitamin D and Mineral Homeostasis in Very Premature Infants Fed Preterm Human Milk

Abstract

Fourteen very low birthweight infants (mean .+-. SD 1,070 .+-. 180 g and 29.3 .+-. 1.9 wk gestation) fed their own mother''s milk were clinically followed until 3-4 mo. of age with frequent measurements of serum Ca, P, Mg, 25-hydroxyvitamin D (25-OHD), parathyroid hormone, alkaline phosphatase, and albumin, and urine Ca, P, and Mg. These infants were matched for birthweight and gestation with 14 infants (1,075 .+-. 152 g and 29.0 .+-. 1.7 wk) who had been similarly followed during concomitant studies of infants fed standard formula (Similac 20 cal/oz). Urine P was markedly lower in the breast milk-fed group from initiation of feedings, and serum P became significantly lower at and after 6 wk of age. The fall in serum P was accompanied by a marked calciuria. Parathyroid hormone was suppressed in the breast milk-fed group, although serum Ca was not elevated and did not differ from formula-fed infants. A high incidence of moderate-severe hypomineralization on radiographs was seen in both breast milk- and formula-fed groups. Six of 14 breast-fed infants required P supplementation at 8-10 wk of age because of significant hypophosphatemia, hypercalciuria, and hypomineralization. These infants differed from those not requiring P supplements by being smaller at birth but not of lower gestation, and having persistently low serum 25-OHD at and after 6 wk of age.