Should We Replete Marginally Low Magnesium Levels?

Although low magnesium (Mg) levels might be associated with tachyarrhythmias, a 2015 meta-analysis did not show benefit for repleting low Mg levels in critically ill patients. Nonetheless, many hospitals’ protocols call for Mg repletion to achieve Mg levels higher than 2.0 mg/dL; other hospitals don’t replete until levels drop below 1.4 mg/dL (see Figure 1).

Now, investigators used a quasi-experimental design with a cohort of 170,000 adult patients in intensive care units (ICUs) across >90 U.S. and European hospitals to assess nearly one half million Mg levels. They compared patients who received or didn’t receive intravenous Mg supplementation within 8 hours (mean, 2.6 hours) for Mg levels near (i.e., within 0.5 mg/dL) the treatment …