Thyroid Hormone in Women with Premature Ovarian Insufficiency: A Case-Control Study

To compare thyroid function in patients with premature ovarian insufficiency (POI) with control women of reproductive age and to look into the potential association between thyroid function and metabolic markers in POI patients.

This cross-sectional case-control study enrolled 227 initially diagnosed POI patients and 232 controls with regular menstrual periods, all aged 20-40 years. Serum levels of thyroid hormones were compared between the two groups. In women with POI, further correlation analysis of thyroid function with sex hormones and metabolic markers was conducted.

Women with POI exhibited higher serum concentrations of free triiodothyronine (FT₃) (4.43 ± 0.55 pmol/L vs 4.22 ± 0.48 pmol/L, P < 0.001), free thyroxine (FT₄) (14.07 [12.93, 15.37] pmol/L vs 13.11 [12.31, 13.87] pmol/L, P < 0.001), and a higher proportion of thyrotropin (TSH) ≥ 2.5 mIU/L (22.47% vs 15.09%, P = 0.043) than controls, with all values remaining within the normal reference range. Elevated serum levels of FT₃ and FT₄ were positively associated with POI. In POI patients, weak positive correlations of blood glucose with both FT₃ and FT₄ were observed, whereas no significant associations were found with other metabolic markers.

This study indicated that higher levels of thyroid hormones, with statistically significant but clinically subtle differences within normal ranges, were positively associated with POI. In women with POI, thyroid hormone levels also showed a weak positive correlation with blood glucose. Further investigation is needed to clarify the clinical significance of these findings.