Association of Subclinical Hypothyroidism with Reproductive, Metabolic, and Molecular Dysfunction in Polycystic Ovary Syndrome

OBJECTIVE: To assess the influence of subclinical hypothyroidism (SCH) on hormonal balance, metabolic parameters, and the expression patterns of thyroid-stimulating hormone (TSH), androgen receptor (AR), and proopiomelanocortin (POMC) genes in women with polycystic ovary syndrome (PCOS). STUDY DESIGN: A cross-sectional observational study. Place and Duration of the Study: Obs & Gynea Department, Shaikh Zayed Hospital, Lahore, Pakistan, from August 2024 to April 2025. METHODOLOGY: Women aged 20-40 years with PCOS and normal thyroid function (n = 35), PCOS with SCH (n = 35), and healthy women serving as controls (n = 35) were recruited. Clinical, anthropometric, and reproductive data were obtained. Biochemical and hormonal parameters were measured, including fasting glucose, lipid profile, glycated haemoglobin (HbA1c), luteinising hormone (LH), follicle-stimulating hormone (FSH), testosterone, TSH, free thyroxine (T4), and free triiodothyronine (T3). Quantitative PCR was performed for gene expression of TSH, AR, and POMC. Normality of the data was checked using the Shapiro-Wilk test with SPSS version 22. One-way ANOVA or the Kruskal-Wallis test was used to compare differences among the three groups, followed by Tukey's test or Dunn's test with Bonferroni correction for post hoc analysis. The chi-square test was used to assess associations between categorical variables. RESULTS: Women with PCOS-euthyroid and PCOS-SCH had significantly higher BMI (p <0.001) and irregular menstrual cycles (p <0.001) than the control group. TSH was higher (p <0.001) in the PCOS-SCH group (8.80 ± 1.31) compared to the PCOS-euthyroid (2.91 ± 0.56) and control (2.54 ± 0.55) groups. Patients in the PCOS-SCH and PCOS groups demonstrated higher levels (p <0.001) of LH (12.82 ± 1.02 and 13.79 ± 0.66 mIU/mL), testosterone (80.49 ± 6.81 and 100.27 ± 26.87 ng/dL), prolactin (36.37 ± 7.15 and 26.77 ± 2.24 ng/dL), and dyslipidaemia, as well as elevated HbA1c (6.04 ± 0.22 and 6.04 ± 2.0), compared to the control group. However, FSH was lower (p <0.001) in the PCOS groups. Gene expression analysis revealed higher (p <0.01) TSH expression in the PCOS-SCH group compared to the other groups. The median AR expression (2-∆∆CT) was significantly higher (p <0.05) in the PCOS-euthyroid group (2.12) compared to the control group (0.30). Similarly, median POMC expression (2-∆∆CT) was significantly higher (p <0.001) in both groups than in the control group. CONCLUSION: SCH in PCOS may worsen clinical, hormonal, and metabolic disturbances and is associated with elevated TSH, AR, and POMC gene expression, potentially increasing cardiometabolic and reproductive risks. Key Words: Polycystic ovary syndrome, Subclinical hypothyroidism, Gene expression, Androgen receptor, Proopiomelanocortin.