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Elevated fasting irisin levels observed in adolescents with PCOS
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Lean, sedentary adolescents with polycystic ovary syndrome have higher levels of fasting serum irisin vs. adolescents without PCOS, even after controlling for BMI, according to findings published in Clinical Endocrinology.
“Given that most PCOS patients have a tendency to become insulin resistant, it has been speculated that irisin, a newly discovered myokine that improves glucose tolerance and alleviates insulin resistance in mice, may play a role in the development of PCOS and may also represent a novel PCOS biomarker,” Flora Bacopoulou, MD, PhD, assistant professor of pediatrics-adolescent medicine at the Center for Adolescent Medicine at National and Kapodistrian University of Athens, Greece, and colleagues wrote. “Irisin can cause energy expenditure and weight loss by converting the stored white adipose tissue to brown adipose tissue and inducing thermogenesis in mice.”
Bacopoulou and colleagues analyzed data from 23 adolescent girls and women with PCOS aged 13 to 21 years (mean age, 17 years; mean BMI, 20.9 kg/m²), as well as 16 age- and BMI-matched controls without PCOS (mean age, 18 years; mean BMI, 20.3 kg/m²) between January 2015 and January 2016. All included participants reported not engaging in regular exercise during the past 6 months. Participants underwent ovarian measurements and provided fasting blood samples to measure serum irisin, follicle-stimulating hormone, luteinizing hormone, estradiol, testosterone, delta 4-andostenedione, dehydroepiandrosterone sulfate, 17-hydroxyprogesterone (17-OHP) and sex hormone-binding globulin. Researchers used linear and multiple regression models to assess which variables were dependently and independently associated with irisin.
Compared with controls, researchers found that adolescents with PCOS had higher levels of serum irisin (mean, 1.7 µg/mL vs. 1 µg/mL), as well as higher levels of luteinizing hormone (P = .027), estradiol (P = .009), testosterone (P < .001), delta 4-andostenedione (P = .016), 17-OHP (P = .01), glucose (P = .03), Ferriman-Gallwey score (P < .001) and mean ovarian volume (P < .001).
For the total cohort, researchers found that serum irisin levels were positively correlated with glucose (r = –0.428; P = .007), insulin (r = –0.369; P = .021), homeostatic model assessment of insulin resistance (r = –0.422; P = .007) and negatively correlated with quantitative sensitivity check index (r = –0.329; P = .041).
In multiple regression analysis, follicle-stimulating hormone and mean ovarian volume were positive predictors of serum irisin concentrations, and luteinizing hormone and testosterone were negative predictors, according to researchers. In simple linear regression analysis, serum irisin was a positive predictor of fasting glucose in the total sample.
“Although the mechanisms that contribute to the elevated serum irisin in adolescent PCOS should bear further investigation, our results suggest that the myokine irisin was associated with the adolescents’ metabolic and reproductive characteristics and the hyperandrogenic phenotype of the syndrome,” the researchers wrote. – by Regina Schaffer
Disclosures: The authors report no relevant financial disclosures.
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