Serum irisin concentrations in lean adolescents with polycystic ovary syndrome

ObjectiveTo explore differences in irisin concentrations between lean adolescents with PCOS and age- and body mass index (BMI)-matched controls and examine the associations of irisin with core features of the syndrome. DesignCross-sectional study. PatientsLean females with PCOS, aged 13-21years. MeasurementsPhysical, hormonal and sonographic assessment. Irisin concentrations were measured with ELISA. ResultsParticipants included in total 39 sedentary females (meanSD; age 17.3 +/- 2.1years, BMI 20.7 +/- 1.3 Kg/m(2)), 23 adolescents with PCOS and 16 controls. Adolescents with PCOS compared to controls had significantly elevated concentrations of fasting serum irisin (mean +/- SD; PCOS, 1.7 +/- 1.0g/mL vs controls, 1.0 +/- 0.4g/mL; P=.007), luteinizing hormone (LH), oestradiol, testosterone, 4-androstenedione, 17-hydroxyprogesterone, glucose, as well as free androgen index, Ferriman-Gallwey score and mean ovarian volume (MOV). For the total sample, circulating irisin was positively correlated with MOV (r=.332, P=.041), glucose (r=.428, P=.007), insulin (r(s)=.369, P=.021) and HOMA-IR (r(s)=.422, P=.007) and negatively correlated with QUICKI (r=-.329, P=.041). Follicle-stimulating hormone (B=0.295, Beta=.342, P=.042) and MOV (B=0.182, Beta=0.821, P=.001) were positive predictors, and LH (B=-0.108, Beta=-0.523, P=.010) and testosterone (B=-0.431, Beta=-0.457, P=.032) were negative predictors of irisin concentrations, whereas irisin positively predicted fasting glucose (B=0.262, Beta=0.428, P=.007). In the PCOS group, irisin concentrations were positively correlated with HOMA-IR (r(s)=.416, P=.048) but negatively correlated with LH (r(s)=-.499, P=.015), testosterone (r=-.585, P=.003), free androgen index (r=-.426, P=.048) and Ferriman-Gallwey score (r=-.533, P=.015). ConclusionsIrisin was associated with the adolescents' metabolic and reproductive characteristics and the hyperandrogenic phenotype of the syndrome. Much research is needed to ascertain mechanisms of elevated serum irisin in adolescent PCOS.