Calcium and phosphorus needs of premature infants

Abstract

Interpretation of the available studies for the purpose of predicting the recommended Ca and P needs of LBW infants is difficult because of the number of confounding variables that can affect Ca and P metabolism. Clinically, the most important measure of Ca/P 'adequacy' must also be determined. Clearly, the predicted recommended intakes for dietary Ca and P would be different if normalization of serum and urine Ca and P levels is chosen rather than achievement of intrauterine retention of mineral or bone mineral content as the index of adequacy of mineral intake. The factorial approach to the estimation of Ca/P requirements was previously proposed by Ziegler et al. A reevaluation of their estimation is warranted in the light of recent data on estimates of fetal accretion of minerals in the third trimester (2.9 used by Zeigler et al.) vs. 3.7 estimated by Widdowson et al. and reported efficiencies of absorption of various sources of Ca and P in feedings for LBW infants. Based on the observed differences in bioavailability of Ca and P from different salts and combined with various milks, it may be appropriate to recommend intakes of Ca and possibly P that are specific for premature formulas separate from that recommended for supplements to preterm mother's milk.