Hospital patients in the normal range for magnesium have a higher risk of dying than those given extra supplements.
April 24, 2026
Original Paper
Optimal Serum Magnesium Level and Mortality in Critically Ill Patients
SSRN · 6622860
The Takeaway
Doctors traditionally only give magnesium to ICU patients if their levels drop below the official healthy threshold of 1.7 mg/dL. This data shows that mortality is actually lowest at 2.1 mg/dL, which is the very top of the normal range. Patients with levels between 1.7 and 2.1 mg/dL were much more likely to die than those who were given supplements to reach the higher target. This suggests that the medical definition of normal is dangerously low for the critically ill. Adjusting these standards could save thousands of lives in intensive care units every year.
From the abstract
Abstract Background: Magnesium deficiency is common in critically ill patients, and serum-based thresholds may underestimate clinically relevant deficiency within the normal range. The association between magnesium levels and mortality across the full range of values remains incompletely characterized. Objective: To determine the magnesium level associated with the lowest mortality and to assess whether supplementation and early target attainment are associated with improved survival in patien