Persistent Secondary Hyperparathyroidism in Infants Fed Humanized Cow Milk Formula-Reply

In Reply.—The questions of Dr Cunningham are important ones and precisely the reasons for the publication of our findings.¹ As Dr Cunningham astutely observes, the serum parathyroid hormone concentrations were also increased in the formula-fed infants without symptoms, at least in reference to human-milk—fed infants. The report that tetany in infants fed older formulas was followed by enamel hypoplasia in deciduous teeth actually involved a formula with a higher phosphate content relative to the calcium content of that used in our study. Hyperparathyroidism, indeed, might adversely affect the bones and teeth of formula-fed infants. However, the degree of relative elevation of serum parathyroid hormone concentrations achieved in these infants may not be sufficient to cause any lasting ill effect. These are important questions and extremely interesting ones that we are presently pursuing and we hope to report these results in the near future.

Indeed, bottle-fed infants also have