Longitudinal evaluation of serum leptin and bone mineral density in early postmenopausal women

To evaluate total and site-specific bone mineral density (BMD) and serum leptin levels in postmenopausal women treated with a calcium supplement and in postmenopausal women receiving estrogen plus progestin therapy.

Forty-four women were randomized to receive either calcium supplementation (group A, n = 22) or transdermal 17beta-estradiol at a dose of 50 mug/day in a continuous regimen and nomegestrol at a dose of 5 mg/day for 12 days per month in a sequential regimen (group B, n = 22). All women underwent dual-energy x-ray absorptiometry determination of BMD and blood sampling in the morning at the beginning of the study and after 12 months. Leptin was determined by radioimmunoassay in all samples.

After 12 months, serum leptin levels were significantly higher in group A (control) in comparison with group B and baseline values, whereas both total and pelvic BMDs were significantly lower in group A in comparison with group B and baseline values. At baseline, a significant correlation was found between leptin levels, body mass index, and total-body BMD. After 12 months, leptin was still correlated to body mass index in both groups, but the association with BMD was lost.

This study confirms previous evidence of a significant correlation between serum leptin and BMD in early postmenopausal women. Furthermore, this correlation is lost over time during the progression of the postmenopausal period, independently from the administration of estrogen-progestin therapy. Further studies and longer follow-up periods are needed to better understand theses issues.