Sir.—Would Venkataraman and colleagues1 discuss the long-term implications of persistent secondary hyperparathyroidism in infants fed humanized cow milk formula?
Their observation was prompted by the appearance of tetany in formulafed infants, but serum parathyroid hormone levels were also increased in formula-fed infants without symptoms. Tetany in infants fed older formulas is followed by enamel hypoplasia in deciduous teeth2; and even without tetany young children fed formula as infants have twice as much dental caries as their breast-fed counterparts.3
As Venkataraman et al1 observe, all bottle-feeds have excessive phosphorus and, to a lesser degree, excessive calcium compared with human milk. In the long run is this likely to produce more bone mineral, less bone mineral, or qualitatively different bone mineral? In at least two animal species high calcium intakes and increased mineral retention in early life produce less stable bone mineral and greater calcium loss during