733 REDUCTION OF SERUM IONIZED CALCIUM (iC) AND ELEVATION OF SERUM PHOSPHORUS IN COW MILK FORMULA FED INFANTS COMPARED TO BREAST FED INFANTS IN THE FIRST SIX MONTHS OF LIFE

Abstract

Cow milk may result in neonatal hypocalcemic tetany in term infants at one wk of age. Current US cow milk formulas are modified to have lower P contents and should minimize adverse effects on Ca metabolism. However these formulas still contain more P (33-40 mg/dl) vs breast milk (13 mg/dl) and there are no studies on iCa and P in formula vs breast fed infants in the first 6 mos of age. We hypothesized that the higher intake of P in formula vs breast fed infants results in greater serum P but lower iCa. In a 2⁴ factorial design cross-sectional study controlled for sex, race, season and diet, we evaluated serum Ca, iCa and P by diet (formula vs breast) in 119 normal, term infants <6 mo of age. No differences in serum Ca, iCa or P by season, race or sex were found. Total serum Ca did not differ between breast- and bottle-fed with means (±sem) of 9.75 (0.09) and 9.73 (0.06) mg/dl. However, iCa (Radiometer electrode, N adults 4.8-5.2 mg/dl, CV 1.1-2.6%) was lower in bottle- (5.27±0.02 mg/dl) vs breast-fed infants (5.38±0.03) (p=0.005). Serum P was higher (6.98±0.08) for bottle- vs 6.44 (±0.10) in breast-fed (p<0.001). There were no correlations of C-terminal or intact PTH by radioimmunoassay with iCa or P. Thus, serum iCa is lower and P is higher in formula- vs breast-fed infants. We speculate that the lower Ca:P ratio in cow milk formula (1.3:1) compared to that of breast milk (2:1) may be responsible for these observed differences.

Log in or create a free account to read this content

Gain free access to this article, as well as selected content from this journal and more on nature.com

Access through your institution

or

Sign in or create an account

Continue with Google

Continue with ORCiD