Objective:

To investigate if thyroid autoimmunity (TAI) distinguishes a metabolically or androgenically more severe phenotype of polycystic ovary syndrome (PCOS) and to clarify its clinical significance.

Key Findings:

• No significant association between TAI and primary outcome (TG/HDL >3.5) (OR 0.77, 95% CI 0.21–1.67).
• No notable associations for secondary outcomes including non-HDL-C ≥130 mg/dL (OR 1.09, 95% CI 0.61–1.76) or impaired glucose tolerance (OR 1.27, 95% CI 0.63–2.18).
• Findings were consistent across various definitions of TAI and sensitivity analyses, reinforcing the reliability of the results.

Interpretation:

Thyroid autoimmunity does not appear to correlate with a more severe cardiometabolic or androgenic phenotype in women with PCOS, suggesting that TAI may not be a useful marker in clinical practice.

Limitations:

• Cross-sectional design limits causal inference; future studies should consider longitudinal designs.
• Findings may not be generalizable beyond the studied population; replication in diverse cohorts is needed.

Conclusion:

Thyroid autoimmunity does not distinguish a metabolically high-risk subgroup of PCOS; further longitudinal studies are needed to explore long-term effects and potential clinical implications.