Plasma Leptin Concentrations in Postmenopausal Women with Osteoporosis

Abstract

Osteoporosis is less common in obese individuals with increased bone mineral density (BMD) andplasma leptin concentrations. The aim of this study was to determine the correlation between leptin levelsand BMD in postmenopausal women. The study consisted of 90 postmenopausal women with a meanage of 53.45 ± 0.87 years who visited our outpatient clinic for the evaluation of BMD. Thirty-six postmenopausalwomen with osteoporosis (mean age: 54.52 ± 1.41 years and mean body mass index(BMI, kg/m2) 29.33 ± 0.66), 30 age- and BMI-matched postmenopausal women with normal BMD,and 24 postmenopausal women (mean age: 52.79 ± 1.48 years and mean BMI: 29.45 ± 0.89) withosteopenic BMD were included in the study. Plasma concentrations of leptin after an overnight fastwere measured by radioimmunoassay. BMD values were measured by dual-energy X-ray absorptiometry(DEXA) at the L2-L4 lumbar spine and femoral neck. The median spine BMD value in the patientgroup (0.67 ± 0.08 g/cm2, mean ± SEM) was significantly lower than that in the controlgroup (1.02 ± 0.25 g/cm2, mean ± SEM ) and osteopenic group (0.87 ± 0.05 g/cm2, mean ± SEM)(p < 0.005). The mean spine BMD value (T score −3.63 ± 0.25, mean ± SEM) and the mean femurneck BMD value (T score −2.55 ± 0.18, mean ± SEM) of the osteoporosis group were significantlylower than that in the normal BMD group (+ 0.33 ± 0.14 and + 0.27 ± 0.18, p < 0.001) and in theosteopenia group (−1.74 ± 0,1 and –1.18 ± 0.05, p < 0.005). The mean plasma leptin concentrationin the osteoporotic group (17.03 ± 1.40 ng/ml) was not significantly different from that in the normalBMD group and the osteopenia group (16.55 ± 1.50 ng/ml; 16.16 ± 1.60, respectively, p < 0.150).Plasma leptin concentrations were correlated with BMI in three groups (r(s) = 0.450, p = 0.025 innormal BMD group and r(s) = 0.4254, p = 0.009 in the osteoporotic group, and r(s) = 395, p = 0.015in the osteopenia group. There was no correlation between plasma leptin concentrations and BMD valuesin three groups (r(s) = −0.89 in normal BMD group, r(s) = −0.124 in osteopenia group, andr(s) = −0.195 in osteoporosis group). From this study we conclude that circulating plasma leptin doesnot have a significant direct influence on bone mass in postmenopausal women.