Brown adipose tissue activity is reduced in women with polycystic ovary syndrome

To evaluate whether brown adipose tissue (BAT) activity is altered in women with polycystic ovary syndrome (PCOS), and whether BAT activity correlates with plasma levels of irisin, a myokine that can induce BAT formation.We performed a cross-sectional study including women with PCOS (n = 45) and a healthy control group (n = 25) matched by age and body mass index (BMI).BAT activity was measured using 18F-FDG positron emission tomography-computed tomography (PET-CT) and plasma irisin levels were measured by a validated enzyme immunoassay.Total BAT activity was significantly reduced in women with PCOS (maximal standardized uptake value (SUVmax): median 7.4 g/mL, interquartile range 0.9-15.4) compared to controls (median 13.0 g/mL, interquartile range 4.7-18.4, P = 0.047). However, this difference was no longer significant after adjustment for waist circumference, a surrogate marker of central adiposity. In the PCOS group, BAT activity correlated negatively with BMI (Spearman's r = -0.630, P = 0.000) and waist circumference (r = -0.592, P = 0.000) but not with plasma irisin levels.BAT activity was reduced in women with PCOS possibly due to increased central adiposity. In PCOS women, BAT activity did not correlate with plasma irisin levels.