Calcium-regulating hormones and minerals from birth to 18 months of age: a cross-sectional study. II. Effects of sex, race, age, season, and diet on serum minerals, parathyroid hormone, and calcitonin.

The influence of sex, race, age, season, and diet (cow's milk formula v human milk) on serum minerals and calcium-regulating hormones in infants less than 18 months of age is described in this study of 198 infants. No sex differences were observed in calcium, magnesium, phosphorus, parathyroid hormone, or calcitonin concentrations. Black infants had decreased serum phosphorus concentrations compared with white infants. There was a decrease in serum ionized calcium and phosphorus levels with age. During winter, there were significant increases in serum calcium and magnesium and decreases in serum phosphorus, parathyroid hormone, and calcitonin levels. Formula-fed infants had increased serum phosphorus and decreased ionized calcium concentrations compared with infants fed human milk. Thus, race, age, season, and diet appear to exert significant effects on serum minerals and calcium-regulating hormones in infancy. Interpretation of these mineral and hormone concentrations in normal or diseased states should be based on normative data specific to race, age, season, and diet.