[Calcium, phosphorus and vitamin D administration in infancy. Unsolved questions]

In premature infants calcium and phosphate supplementation should be continued until the infants weigh more than 2000 g, because osteopenia of prematurity has been described after discontinuation of the supplements at body weights of < 1800 g. Premature infants generally receive substantially more vitamin D than their daily requirements (> 400 IU), but then are no studies on the side effects of high vitamin D intake (hypercalciuria?). The extremely high calzitriol concentrations in plasma of premature infants who receive Ca/P supplements indicate that maximal stimulation of Ca/P absorption is necessary and present supplementation could still be inadequate. The daily vitamin D requirements of term infants are between 100 and 400 IU and no supplements are necessary if the infants are fed vitamin-D-fortified formulas. The high prevalence of rickets in infants on macrobiotic or vegetarian diets indicates that those infants should receive calcium and vitamin D supplements.