Women's fertility and vitamin D: Could hypovitaminosis D biomarkers correlate with the disease, and explain the unexplained female factor infertility?

Objective: Vitamin D (Vit D) deficiency correlates women reproductive pathophysiology. We analyzed Vit D deficiency biomarkers in infertile women. Patients & method: This case-control study enrolled 80 infertile women polycystic ovary syndrome (PCOS), and other etiologies; anovulation and unexplained and 25 controls. Serum calcidiol and calcitriol were determined by ELISA and their direct ratio was calculated. Results: 72% of controls and 92.5% of patients had Vit D deficiency/insufficiency (calcidiol mean ± SDM of 33.50±22.10 vs. 20.26±5.226 ng/mL and an AUC of 0.808±0.048). Calcitriol had an AUC of 0.909±0.031 that more effectively distinguished patients and etiologies (53.49±23.30 pg/mL) from controls (114.0±43.20 pg/mL; P<0.001). 4 other etiology cases and 17 controls had calcitriol levels ≥100 pg/mL. 64% of controls (4.090±0.020) and 16.25% of patients [2.634±0.855, P<0.04; 5 PCOS (3 primary/2 secondary), 3 secondary unexplained, and 5 others (one primary tubal, one primary/one secondary peritoneal, one primary/one cervical and one primary tubal had a normal ratio ≥3.333 at an AUC of 0.740±0.065. All biomarkers revealed patient levels ~50% lower than controls; lowest in PCOS and unexplained etiologies. Conclusion: Vit D levels are significantly reduced in infertile women; lowest in PCOS and unexplained etiology, for all biomarkers, where calcitriol was the optimal predictor of both infertility and etiology.