Assessment of serum vitamin D and testosterone levels in women with polycystic ovary syndrome in Babylon Province, Iraq: a case–control study

Introduction: Polycystic ovary syndrome (PCOS) is one of the most frequent endocrine and metabolic disorders of women of reproductive age and is characterized by androgen excess, ovulatory dysfunction and polycystic ovarian morphology, frequently accompanied by insulin resistance and excess adiposity. Vitamin D and calcium status — conditions central to nutrology and closely linked to dietary pattern, body weight and physical activity — may modulate insulin sensitivity and androgen metabolism in this population. Objective: To compare serum vitamin D, testosterone and calcium concentrations between women with PCOS and healthy women in Babylon Province, Iraq, and to identify the demographic, nutritional and lifestyle factors associated with PCOS. Methods: This case–control study, reported in accordance with the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) statement, included 80 women recruited from hospitals in Babylon Province between October 2023 and April 2024: 40 women with PCOS and 40 healthy controls. Serum vitamin D and testosterone were measured by enzyme-linked immunosorbent assay (ELISA) and serum calcium by spectrophotometry. Body mass index (BMI) was classified per World Health Organization criteria. Means were compared by the independent-samples t-test and proportions by the chi-square test; crude and adjusted odds ratios (OR) with 95% confidence intervals (CI) were derived from univariate and multivariable logistic regression, and correlations were examined with Pearson's coefficient; P < 0.05 was significant. Results: Women with PCOS had significantly lower serum vitamin D (19.74 ± 6.68 vs. 26.42 ± 6.85 ng/mL; P < 0.001) and calcium (7.77 ± 0.92 vs. 9.46 ± 1.71 mg/dL; P < 0.001) and higher testosterone (1.28 ± 0.42 vs. 1.02 ± 0.24 nmol/L; P < 0.001) than controls. Overweight and obese women constituted 65.0% of the PCOS group versus 30.0% of controls (P = 0.005). In univariate analysis rural residence (OR = 2.64; 95% CI: 1.04–6.69), overweight (OR = 3.25; 95% CI: 1.09–9.66), obesity (OR = 6.50; 95% CI: 1.79–23.64), physical inactivity (OR = 3.12; 95% CI: 1.25–7.78), smoking (OR = 4.75; 95% CI: 0.94–23.99) and irregular diet (OR = 6.64; 95% CI: 1.73–25.47) were associated with PCOS; after multivariable adjustment only obesity (adjusted OR = 4.65; 95% CI: 1.01–21.40) and irregular diet (adjusted OR = 4.95; 95% CI: 1.18–20.85) remained independently associated. BMI correlated positively with testosterone (r = 0.364; P = 0.001) and negatively with calcium (r = −0.266; P = 0.017), and vitamin D correlated positively with calcium (r = 0.388; P < 0.001). Conclusion: Women with PCOS in Babylon Province show vitamin D deficiency, lower serum calcium and higher testosterone than healthy women, and obesity and an irregular diet are the factors independently associated with the syndrome. These findings support the inclusion of nutritional assessment, vitamin D and calcium evaluation, and weight and dietary counselling in the care of women with PCOS. Because the sample was small and the confidence intervals wide, the associations should be regarded as hypothesis-generating and confirmed in larger studies.