Serum magnesium is associated with osteoporosis risk in postmenopausal women: a retrospective study and risk-prediction model.

Objective: To investigate the association between serum magnesium (Mg) levels and osteoporosis (OP)/osteoporotic fractures in postmenopausal women, and to develop a multi-parameter model for predicting OP risk. Methods: This retrospective study included 496 hospitalized postmenopausal women from January 1, 2021 to June 30, 2025. Patients were categorized into the OP group (T-score ≤ -2.5) and the non-OP group ( Results: Among 496 participants, 208 were classified as non-OP and 288 as OP. Osteoporotic fractures were identified in 31 patients, while 465 had no osteoporotic fractures. patients with OP were older, had lower body mass index (BMI), lower BMD, and lower serum Mg and P levels. ROC analysis showed modest discrimination for Mg (AUC 0.602, 95% CI 0.551-0.652), with an optimal cut-off of 0.845 mmol/L. After adjustment for potential confounders, Mg ≤ 0.845 mmol/L was independently associated with higher odds of OP (OR 1.940, 95% CI 1.312-2.868; Conclusion: Lower serum Mg levels were associated with OP and osteoporotic fractures in hospitalized postmenopausal women. Mg may support OP risk stratification, and a multi-parameter model integrating clinical and bone metabolism-related markers may further improve risk assessment.