Impact of subclinical hypothyroidism on clinical, hormonal, and metabolic parameters in women with polycystic ovary syndrome: the role of levothyroxine therapy

Polycystic Ovary Syndrome (PCOS) is a prevalent endocrine disorder in women of reproductive age, often associated with metabolic abnormalities. Subclinical Hypothyroidism (SCH) frequently coexists in women with PCOS; however, its clinical and metabolic implications remain inadequately defined. This study aimed to determine the prevalence of SCH in women with PCOS and assess its impact on clinical, hormonal, and metabolic parameters, as well as the potential benefits of levothyroxine therapy. A cross-sectional study was conducted at Azadi Teaching Hospital in Duhok, Iraq, involving 139 women diagnosed with PCOS. Participants were categorised into three groups: euthyroid (n = 95), untreated SCH (n = 24), and treated SCH (n = 20). Clinical features and biochemical markers, including Fasting Blood Sugar (FBS), lipid profile, reproductive hormones, and blood pressure, were evaluated. SCH was identified in 31.7% of participants. The untreated SCH group had a lower median FBS (90.5 mg/dL) than the euthyroid group (92 mg/dL), with a further reduction in the treated group (86.5 mg/dL). Subfertility was most prevalent in the euthyroid group (56.7%) compared to the treated (30.0%) and untreated (13.3%) SCH groups (p = 0.025). Acne was significantly more common in the euthyroid group (71.1%) than in the untreated (20.6%) and treated (8.2%) groups (p = 0.004). Diastolic blood pressure (DBP) was highest in the treated SCH group (80.5 mmHg; p = 0.002), and a weak but significant correlation was observed between Thyroid-Stimulating Hormone (TSH) and DBP (ρ = 0.231, p = 0.006). These findings suggest that SCH is prevalent among women with PCOS, and levothyroxine therapy may contribute to improved clinical and metabolic outcomes.

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