Independent effect of endogenous dehydroepiandrosterone-sulphate levels and birth weight on bone turnover parameters in young adults.

Data indicate that bone turnover is higher in young adults born with a low birth weight (LBW). Moreover, several data support the presence of altered adrenal hormone production in this population. The aim of our study was to investigate whether there is any connection between altered bone homeostasis and adrenal hormone levels. Bone mineral density (BMD), serum osteocalcin (OC), and urinary deoxypyridinoline (DPD) excretion were related to dehydroepiandrosterone-sulphate (DHEAS), cortisol, estradiol, testosterone, and sex-hormone binding globulin (SHBG) levels in 47 healthy young women (of those, 33 were LBW) and 65 healthy young men (of those, 49 were LBW). The age of the subjects was 19-21 years. BMD values were normal and did not correlate with any of the factors investigated. Cortisol did not have any independent effect on bone turnover parameters in either men or women. In women, birth weight, DHEAS levels, and free estradiol index were responsible for almost 50% (corrected r2= 0.45) of serum OC variability. Independent positive associations were observed between DHEAS and OC, and between DHEAS and DPD excretion. In men, birth weight and DHEAS levels together were responsible for more than one-third (corrected r(2) = 0.36) of the variability of serum OC. In contrast with women, DHEAS and OC were inversely correlated in men. Our results suggest that bone turnover depends on the subjects' birth weight. Moreover, DHEAS is also an independent determinant. The effect of DHEAS on bone turnover is different in women and men. DHEAS increases bone turnover in fertile women, while it decreases this in men.