Serum irisin levels in women with polycystic ovary syndrome: a cross-sectional case-control study.

BACKGROUND: Polycystic ovary syndrome (PCOS) is a common endocrine-metabolic disorder. Irisin is an exercise-related myokine involved in energy homeostasis; however, prior studies have reported inconsistent associations between irisin and PCOS. OBJECTIVES: To compare serum irisin levels between women with PCOS and non-PCOS controls and to assess the discriminatory performance of irisin for PCOS. DESIGN AND SETTING: Cross-sectional, case-control study conducted at a tertiary referral center. METHODS: We enrolled 144 women, 72 with PCOS and 72 non-PCOS as controls. Serum irisin levels were measured using an enzyme-linked immunosorbent assay. Adjusted comparisons were performed using a general linear model, and the association between irisin and PCOS was further evaluated using multivariable binary logistic regression. Receiver operating characteristic (ROC) analysis was used to assess the diagnostic performance of irisin. RESULTS: Serum irisin levels in the PCOS group were significantly lower than those in the control group (p = 0.006). In the age and body mass index (BMI) adjusted ANCOVA model, PCOS status remained significantly associated with lower log-transformed irisin (p = 0.002). In a multivariable logistic regression analysis adjusted for age and BMI, log-transformed irisin levels remained independently associated with PCOS (p = 0.006). In ROC analysis, the area under the ROC curve for irisin was 0.632; an irisin cut-off of ≤ 16.2 ng/mL resulted in 87.5% sensitivity and 38.89% specificity. CONCLUSIONS: Women with PCOS had lower circulating irisin levels than controls, and this association persisted after adjusting for age and BMI. Discriminatory performance was modest, and specificity was low at the selected cutoff. Larger studies are warranted to validate these findings.