Serum Vitamin D and Calcium Status among Reproductive and Postmenopausal Women: A Comparative Cross-sectional Study

Background: Vitamin D and calcium are critical for skeletal integrity and systemic health.Despite abundant sunlight, vitamin D deficiency is widespread among Indian women due to lifestyle and physiological factors.This study aimed to compare serum vitamin D and calcium levels among reproductive-age and postmenopausal women, and to examine the prevalence patterns and determinants of deficiency.Materials and methods: A cross-sectional study was conducted among 110 women (55 reproductive-age: 18-45 years; 55 postmenopausal: 45 years) attending a tertiary care hospital in Lucknow.Sociodemographic data, dietary intake, sunlight exposure, and supplement use were recorded.Serum vitamin D was measured using chemiluminescence immunoassay (CLIA); calcium via the Arsenazo III method.Statistical analysis included t-tests, Chi-square tests, and multivariate regression.Results: Mean serum vitamin D was significantly higher in reproductive-age women (26.4 8.1 ng/mL) compared to postmenopausal women (19.2 7.6 ng/mL) (p < 0.001).Vitamin D deficiency (<20 ng/mL) was observed in 25.5% of reproductive-age and 58.2% of postmenopausal women.Mean calcium levels were also higher in reproductive-age women (9.2 0.4 mg/dL) compared to postmenopausal women (8.8 0.5 mg/ dL) (p = 0.002).Multivariate regression showed age-group, body mass index (BMI), sunlight exposure, and dietary intake as significant predictors of serum vitamin D and calcium levels.Conclusion: Vitamin D and calcium deficiencies are prevalent among Indian women, with postmenopausal women disproportionately affected.Routine screening, targeted supplementation, and public health strategies emphasizing dietary diversification and safe sunlight exposure are warranted to improve bone health across the lifespan.