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

Objective: 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.

Design: 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).

Methods: 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.

Results: 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.

Conclusions: 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.