Hypermagnesemia and mortality in COPD patients

Background: Magnesium, the second most abundant intracellular cation, is essential for enzymatic reactions, neuromuscular function, and respiratorion. While electrolyte imbalances are common in intensive care units (ICUs), the effect of magnesium at ICU admission in chronic obstructive pulmonary disease (COPD) patients remains understudied. This study investigated serum magnesium levels and mortality among COPD patients admitted to the ICU, including the need for mechanical ventilation, ventilation duration, and ICU length of stay. Methods: In this retrospective, single-center study, 264 COPD patients admitted to a level 3 ICU between January 2024 and January 2025 were analyzed. Patients under 18 years or receiving magnesium supplementation were excluded. Demographic data, comorbidities, ventilation parameters, ICU stay, and mortality were collected from electronic records. Serum magnesium was measured at ICU admission and categorized as hypomagnesemia, normomagnesemia, or hypermagnesemia. Receiver operating characteristic (ROC) analysis assessed the predictive value of magnesium for mortality. Results: The median age was 72.3 years, and 52.3% were male. Ventilatory support was required in 91.7% of patients, with 40.9% receiving invasive mechanical ventilation (IMV). Hypomagnesemia was present in 43.9%, normomagnesemia in 50.8%, and hypermagnesemia in 5.3% of patients. Mortality occurred in 33.3%. Hypermagnesemia was significantly associated with mortality (p = 0.001), whereas hypomagnesemia was not (p = 0.546). Magnesium showed poor discriminative ability for mortality (Area Under the Curve (AUC) = 0.543), but a threshold >2.39 mg/dL differentiated mortality rates (70% vs. 29.9%, p < 0.001). Independent mortality predictors were Acute Physiology and Chronic Health Evaluation II (APACHE II) score (Odds Ratio (OR) = 1.179), malignancy (OR = 4.735), and IMV requirement (OR = 46.887). Conclusions: Hypermagnesemia on ICU admission is associated with increased mortality in COPD patients, whereas hypomagnesemia is not. Serum magnesium has limited predictive value, and further studies are warranted to clarify its role in critical care. Clinical Trial Registration: ACTRN12625000558426, retrospectively registered.

Mg; COPD; Mortality; Ventilatory support; NIV

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