Serum Levels of Magnesium in Patients with Rheumatoid Arthritis and Its Association with Interstitial Lung Disease

INTRODUCTION: Interstitial lung disease (ILD) is one of the most clinically significant extra-articular manifestations of rheumatoid arthritis (RA), yet the contribution of micronutrient imbalances—particularly magnesium deficiency—to pulmonary involvement remains largely unexplored. This study aimed to characterize serum magnesium levels in patients with RA and to investigate their potential relationship with ILD. METHODS: In this cross-sectional analysis, 425 patients with RA were assessed for clinical features, comorbidities, disease activity, and bone health. Serum magnesium levels were classified as normal or reduced using a 2.0 mg/dL threshold, and ILD was determined by high-resolution computed tomography. Multiple logistic regression evaluated whether magnesium deficiency independently predicted ILD. RESULTS: Although hypomagnesemia clustered with diabetes and poorer bone health, it was not an independent predictor of ILD after adjustment for demographic factors, metabolic comorbidities, and treatments (OR = 1.15; p = 0.736). Increasing age (OR = 1.10; p < 0.001) and male sex (OR = 6.6; p < 0.001) remained strong independent predictors of ILD. Biologic therapy was independently associated with ILD (OR = 9.97; p < 0.001). Age and disease duration were the main determinants of impaired bone status, with older age (OR = 1.04 per year; p < 0.001) and longer disease duration (OR = 1.03 per year; p = 0.008) independently predicting poorer bone health. DISCUSSION AND CONCLUSION: Serum magnesium levels were not independently associated with ILD risk in RA. Although hypomagnesemia correlated with metabolic and skeletal comorbidities, it lost significance in multivariable analyses. Pulmonary and bone outcomes were mainly driven by demographic factors and cumulative disease burden.