Difference in non-weight-bearing effects on bone mineral density between trunk and peripheral fat mass in women with polycystic ovary syndrome.

AIM

To investigate the difference in non-weight-bearing effects on bone mineral density (BMD) between trunk and peripheral fat mass in women with polycystic ovary syndrome (PCOS).

METHODS

Subjects were 123 amenorrheic PCOS women with right side dominance. Age, height, body weight, and body mass index were recorded. Trunk, peripheral (extremities), trunk-leg fat ratio as an index of body fat distribution, left arm (non-weight-bearing site) lean mass and BMD were measured by dual-energy X-ray absorptiometry. Serum testosterone and estradiol levels were measured. Relationships of BMD with trunk, peripheral fat mass, and sex hormones levels were investigated.

RESULTS

Trunk fat mass amount was 9.8 + or - 6.7 kg and was lower than the peripheral fat mass amount (12.2 + or - 4.4 kg, P < 0.01). On Pearson's correlation test, trunk fat mass and left arm lean mass were positively correlated with arm BMD (r = 0.359, P < 0.001 and r = 0.501, P < 0.0001, respectively), while peripheral fat mass and serum testosterone levels were not correlated with BMD (r = 0.083 and 0.114, respectively, NS). On multiple regression analysis, trunk fat mass was positively correlated with BMD (t-value = 3.465; P < 0.001), independent of age and height. However, this relationship disappeared after additionally adjusting for left arm lean mass.

CONCLUSION

Trunk fat mass, despite the smaller amount, is more associated with arm BMD than peripheral fat mass is through its non-weight-bearing effects.