Association Between Serum Magnesium Levels and Severity of Acute Exacerbations in COPD: A Cross-Sectional Study

Background: Magnesium plays an important role in respiratory physiology and has been proposed as a potential biomarker in chronic obstructive pulmonary disease (COPD). However, existing evidence regarding its association with the severity of acute exacerbations (AECOPD) remains inconsistent. This study aimed to evaluate whether serum magnesium levels are associated with clinical severity in hospitalized patients with AECOPD. Methods: In this cross-sectional study, 149 patients admitted with AECOPD in 2024 were classified into mild, moderate, or severe groups based on clinical, physiological, and inflammatory criteria. Serum magnesium levels, arterial pH, oxygen saturation, C-reactive protein (CRP), and other clinical variables were recorded at admission. Between-group differences were assessed using ANOVA and chi-square tests. Correlation analyses and an ordinal logistic regression model were applied to determine whether serum magnesium independently predicted exacerbation severity. Results: AECOPD severity was significantly associated with reduced oxygen saturation, lower arterial pH, higher CRP levels, and longer hospital stay (all P < 0.001). Mean serum magnesium levels did not differ significantly across severity groups (2.15 ± 0.21 mg/dL in mild, 2.07 ± 0.21 mg/dL in moderate, and 2.10 ± 0.29 mg/dL in severe; P = 0.357). Hypomagnesemia (Mg < 1.8 mg/dL) occurred in 7.4% of patients and showed no significant relationship with exacerbation severity (P = 0.873). Correlation analyses demonstrated no significant association between serum magnesium and oxygen saturation, CRP, or arterial pH. In ordinal logistic regression, serum magnesium was not an independent predictor of exacerbation severity (P = 0.960). Conclusion: Although physiological markers clearly differentiated AECOPD severity, total serum magnesium levels remained relatively stable across severity groups and did not independently predict exacerbation severity. These findings suggest that total serum magnesium is unlikely to serve as a reliable standalone biomarker for assessing AECOPD severity. Future studies incorporating ionized or intracellular magnesium measurements are warranted.