Admission serum magnesium levels and the risk of acute respiratory failure

Background: The association between admission serum magnesium (Mg) levels and risk of acute respiratory failure (ARF) in hospitalised patients is limited. The aim of this study was to assess the risk of developing ARF in all hospitalised patients with various admission Mg levels. Methods: This is a single-center retrospective study conducted at a tertiary referral hospital. All hospitalised adult patients who had admission Mg available from January to December 2013 were analysed in this study. Admission Mg was categorised based on its distribution into six groups (less than 1.5, 1.5-1.7, 1.7-1.9, 1.9-2.1, 2.1-2.3 and greater than 2.3 mg/dl). The primary outcome was in-hospital ARF occurring after hospital admission. Logistic regression analysis was performed to obtain the odds ratio of ARF of various admission Mg levels using Mg of 1.7-1.9 mg/dl as the reference group. Results: Of 9780 patients enrolled, ARF occurred in 619 patients (6.3%). The lowest incidence of ARF was when serum Mg within 1.7-1.9 mg/dl. A U-shaped curve emerged demonstrating higher incidences of ARF associated with both hypomagnesemia (< 1.7) and hypermagnesemia (> 1.9). After adjusting for potential confounders, both hypomagnesemia (< 1.5 mg/dl) and hypermagnesemia (> 2.3 mg/dl) were associated with an increased risk of developing ARF with odds ratios of 1.69 (95% CI: 1.19-2.36) and 1.40 (95% CI: 1.02-1.91) respectively. Conclusion: Both admission hypomagnesemia and hypermagnesemia were associated with an increased risk for in-hospital ARF.