Sir.—I wish to comment on the article describing photon absorptiometric measurements of the humerus in term and preterm infants.1 Vyhmeister and coworkers measured the bone mineral content (BMC) of this bone in infants who ranged in weight from 713 to 3779 g and reported, as would be expected, an increase in BMC with increasing birth weight. While such measurements are of use in following the course of infants subjected to various dietary regimens, the question is as follows: How accurately do they reflect the total body calcium content?
A large number of human fetuses (58 in all) have been chemically analyzed for calcium, and these data have been summarized and subjected to mathematical analysis.2 It turns out that total body calcium bears a relationship to body weight and that the fetal body becomes progressively enriched with calcium as gestation proceeds, from 0.57 g of calcium per 100
Forbes GB. Bone Mineral Content in Infants. Am J Dis Child. 1987;141(12):1253-1254. doi:10.1001/archpedi.1987.04460120015015