Betül ÖZTÜRK, Arif Serhan CEVRİOĞLU
Van Medical Journal - 2026;33(4):456-464
Introduction: Polycystic ovary syndrome (PCOS), recently proposed to be renamed polyendocrine metabolic ovarian syndrome (PMOS), is associated with heterogeneous insulin resistance. Vitamin D status has been widely studied in PCOS, but parathyroid hormone (PTH), a calciotropic hormone with potential metabolic relevance, has received less attention. We investigated whether PTH was associated with fasting-derived insulin sensitivity independently of 25-hydroxy vitamin D [25(OH)D3] and whether this association differed by PCOS status. Materials and Methods: In this BMI-matched case-control study, 33 women with PCOS and 30 healthy controls were enrolled. Serum PTH and 25(OH)D3 were measured. HOMA-IR and QUICKI were calculated from fasting glucose and insulin; QUICKI was the primary outcome. Multiple linear regression tested the PTH x PCOS interaction after adjustment for age, BMI, waist-to-hip ratio, and 25(OH)D3. Results: Women with PCOS had higher PTH (53.43+/-20.07 vs 44.42+/-9.81 pg/mL, p=0.030), lower 25(OH)D3 (29.39+/-14.77 vs 36.72+/-6.90 ng/mL, p=0.016), higher HOMA-IR, and lower QUICKI than controls. PCOS modified the PTH-QUICKI association (interaction beta=0.0109; 95% CI 0.0023-0.0196; p=0.014). In controls, higher PTH was associated with lower QUICKI (beta per 10 pg/mL=-0.0106; 95% CI -0.0185 to -0.0027; p=0.009), whereas the corresponding slope in women with PCOS was beta=0.0003 (95% CI -0.0034 to 0.0041; p=0.857). Sensitivity analyses supported the robustness of the interaction. Conclusion: PCOS status modified the association between PTH and fasting-derived insulin sensitivity. The inverse PTH-QUICKI association observed in controls was non-significant in women with PCOS, suggesting altered calciotropic-metabolic coupling.
