Low calcium intake is associated with decreased adrenal androgens and reduced bone age in premenarcheal girls in the last pubertal stages.

Abstract

In 50 premenarcheal girls selected from the lowest and highest end of the calcium-intake distribution of a large population sample, we evaluated bone mineral density (BMD), together with the following hormonal-metabolic parameters: androstenedione (ASD), dehydroepiandrosterone (DHEA), dehydroepiandrosterone sulfate (DHEAS), testosterone (T), estradiol (E2), the apparent free fractions of T (AFTC) and E2 (AFEC), osteocalcin (OC), parathyroid hormone (PTH), and 25-hydroxyvitamin D. Dietary calcium was assessed by 3-day food records, and BMD was measured at ultradistal (ud) and proximal (pr) radial sites, using dual-energy X-ray absorptiometry. Calcium intake, which was below the recommended levels set for the Italian population and below the recommended daily allowance (RDA) in both subgroups of girls, did not show any apparent relationship with ud- and pr- BMD. However, despite the similar chronological age of the two premenarcheal groups, in the low-calcium consumers, we found lower bone age, delayed pubertal development, and lower circulating adrenal androgens. Of interest, in girls who had a low calcium intake, PTH levels were significantly higher. In all premenarcheals, we observed that DHEA, T, and AFTC were positively correlated with bone age and with bone density at both radial sites. Even though bone density at the two radial sites did not show any apparent relationship to calcium consumption, the increased mean PTH in the girls with low calcium intake seems to underscore the hormonal attempt in maintaining calcium homeostasis. In conclusion, low calcium intake and reduced levels of adrenal androgens, leading to decreased bone age and delayed pubertal development, indicate a link between calcium intake, the hormonal milieu, and skeletal maturation.