TOPLINE

Hypomagnesemia affected 13.2% of emergency department (ED) patients; after adjusting for confounding factors, ED patients with hypomagnesemia had a more than 70% higher risk for 30-day mortality than patients with normal magnesium levels. Patients with hypomagnesemia also had higher rates of cardiac arrhythmia, and the risk for arrhythmia increased as the severity of magnesium deficiency increased.

METHODOLOGY

• Using de-identified electronic health record data from the TriNetX Research Network, researchers conducted a retrospective cohort study including 1,246,550 patients aged 18 years or older who presented to the ED between January 2025 and December 2025 and had documented serum magnesium levels.
• Patients were classified into hypomagnesemia (magnesium level ≤ 1.6 mg/dL; n = 164,663) and normal control groups (magnesium level, 1.7-2.2 mg/dL), with hypomagnesemia further stratified into mild (1.3-1.6 mg/dL), moderate (1.0-1.2 mg/dL), and severe (< 1.0 mg/dL) categories.
• Propensity score matching (1:1) was performed for age, sex, race, ethnicity, and comorbidities.
• Mortality within 30 days of the index ED presentation served as the primary outcome; secondary outcomes included 7-day mortality and the presence of arrhythmias such as torsades de pointes, ventricular tachycardia or fibrillation or sudden cardiac arrest, and QT prolongation.

TAKEAWAY

• In unadjusted analyses, patients with hypomagnesemia had nearly twice the 30-day mortality rate of those with normal magnesium levels (3.8% vs 2.0%; odds ratio [OR], 2.0; 95% CI, 1.9-2.0).
• After propensity score matching, the adjusted 30-day mortality remained elevated in the hypomagnesemia group (3.24% vs 1.91%; OR, 1.72; 95% CI, 1.67-1.78), representing a 70% relative increase in the risk for mortality.
• The 7-day mortality rate was higher in patients with hypomagnesemia (1.23% vs 0.76%; OR, 1.64; 95% CI, 1.55-1.72).
• The 30-day arrhythmia rates were higher in the hypomagnesemia cohort after matching (1.58% vs 1.12%; OR, 1.32; 95% CI, 1.27-1.39), with rates increasing as the severity of hypomagnesemia increased.

IN PRACTICE

"This large, observational, real-world study demonstrates that hypomagnesemia was common in the studied population and is independently associated with increased 30-day mortality and rates of potentially lethal arrhythmias after adjustment for measured confounders," the authors wrote.

“Given its association with mortality and its potential for rapid correction, magnesium should no longer be the 'forgotten cation',” they added.

SOURCE

The study was led by Daniel D. Singer, Renaissance School of Medicine, Stony Brook University, New York. It was published online on September 8, 2026, in The American Journal of Emergency Medicine.

LIMITATIONS

The retrospective observational design limited control over unmeasured confounders, including over-the-counter medication use, dietary habits, socioeconomic status, and baseline functional status. Data tracking was restricted to encounters happening within the participating TriNetX facilities, potentially missing events occurring outside the network. The study sample skewed toward large academic medical centers, which may have limited generalizability to smaller rural facilities or medically underserved populations.

DISCLOSURES

The study received no funding. One author reported serving as a senior reviewer for The American Journal of Emergency Medicine but was not involved in the peer review of this article. The other authors reported having no conflicts of interest.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.