Serum adiponectin and resistin in relation to insulin resistance and markers of hyperandrogenism in lean and obese women with polycystic ovary syndrome

Objective: The role of insulin resistance in polycystic ovary syndrome (PCOS) has been established. However the role of adiponectin and resistin in the relationship between insulin resistance as markers of obesity and PCOS has not been conclusive. This study aims to determine the influence of the serum levels of adiponectin and resistin on PCOS, and assess possible correlations with the hormonal and metabolic parameters of the syndrome and obesity. Methods: This study continued a case control study that had finished recruiting 24 subjects of reproductive women with PCOS as a case group, and 24 subjects of normal ovulatory reproductive women without hyperandrogenism as a control group. Further, only 18 subjects of the control group had a body mass index (BMI) <25 kg/m² and were included the data analysis, whereas others were excluded. Therefore, these study data were divided into three groups. Twenty-four PCOS patients from the case group were allocated to two groups, A (n = 14) patients had PCOS + BMI ≥25 kg/m²; B (n = 10) patients had PCOS + BMI <25 kg/m². Group C was the control group of 18 reproductive women without PCOS + BMI <25 kg/m². Blood samples were collected between day 3 and 5 of a spontaneous menstrual cycle, at 07:00 to 09:00, after overnight fasting. Serum levels of follicle-stimulating hormone (FSH), luteinizing hormone (LH), total testosterone, prolactin, sex hormone-binding globulin (SHBG), glucose, insulin, adiponectin and resistin were measured. Results: Serum adiponectin levels were significantly decreased in group A compared with group B and group C. No significant difference existed in adiponectin between group B and group C. Homeostasis Model of Assessment'Insulin Resistance (HOMA-IR) value in group A was found to be significantly higher than group C, but no significant differences were found between group B and group C or between group A and group B. There was no significant difference in serum resistin between all groups, nevertheless the resistin-to-adiponectin (R:A) ratio was significantly decreased in group A compared with groups B and C. In a multiple regression model, BMI, testosterone and insulin resistance were the major determinants of hypoadiponectinemia. However, only BMI was the major determinant of the resistin represented by the R:A ratio. Conclusions: Serum adiponectin levels and the ratio of resistin to adiponectin levels are reduced in obese women with PCOS. These results suggest that, by reducing adiponectin serum level, hyperandrogenemia, together with nutritional status of obesity, might contribute to insulin resistance in the pathogenesis of PCOS.