Association of circulating leptin with bone mineral density in males and females

Leptin, a hormone produced by fat cells, possesses several physiological functions not limited to energy balance. Recently, leptin has been shown to inhibit bone formation through its action at the hypothalamus. In the present study, the authors explored the asssocation of leptin with bone mineral density (BMD) in men and women according to menopausal status. Subjects consisted of 75 men, 51 premenopausal women and 63 postmenopausal women aged 20-80 years. All were healthy and did not take medication which may affect bone metabolism. BMD was measured at L2-4 and femoral neck by DEXA. Serum leptin concentrations were measured by radioimmunoassay. Serum leptin in males was independently related to BMD at L2-4 (r = -0.36, p < 0.05) and the femoral neck (r = -0.32, p < 0.05) in a multiple linear regression model with age, body mass index (BMI), serum free testosterone, estradiol and leptin as independent variables. In premenopausal women, serum leptin correlated negatively to L2-4 (r = -0.29, p < 0.01) and femoral neck BMD (r = -0.29, p < 0.05) independently of age and BMI. However, in postmenopausal women, no association of leptin with BMD was found after controlling for age and BMI. The authors concluded that circulating leptin is negatively associated with BMD in men and premenopausal women, but not in postmenopausal women. The negative associations found in both premenopausal women and men in the present study strengthen the notion that leptin may inhibit bone formation during the accumulation of bone mass early in life.