Mineral Status in Preterm Infants as Measured by Single Photon Absorptiometry

Abstract

An optimal mineral status is difficult to achieve in preterm infants. Multiple nutritional regimens have been used in an attempt to provide sufficient calcium and phosphorus, but have failed generally because of problems with mineral salt solubility. Moreover, when near optimal calcium and phosphorus concentrations are provided in the milk, poor bioavailability of the mineral salt preparations limits appropriate absorption and retention of the minerals (Schanler and Garza, 1988; Schanler et al., 1988). Metabolic bone disease, which occurs as a consequence of inadequate mineral retention, is reported most often in preterm infants fed human milk (Brooke and Lucas, 1985). Preterm infants fed their mothers’ unfortified milk have demonstrated postnatal retention of calcium (Ca) and phosphorus (P) at rates significantly less than estimates of intrauterine mineral accretion (Atkinson, et al., 1983; Rowe et al., 1984). These lowered postnatal Ca and P retentions are of concern. In similar populations of infants, decreased bone mineral content, decreased serum P concentration, increased serum alkaline phosphatase activity, and radiologically determined fractures and rickets also have been reported (Brooke and Lucas, 1985; Atkinson et al, 1983; Rowe et al., 1984; Eek et al., 1957; Gross, 1983; Greer and McCormick, 1988). The conclusion derived from these investigations is that mother’s milk is an inadequate source of Ca and P for preterm infants and that mineral mixtures are needed as fortifiers to achieve more appropriate intakes of Ca and P (Schanler and Garza, 1987).