Increased Mortality Associated with Hypermagnesemia in Severe COVID-19 Illness

Abstract

Background: Although electrolyte abnormalities are common among patients with COVID-19, very little has been reported on magnesium homeostasis in these patients. Here we report the incidence of hypermagnesemia, and its association with outcomes among patients admitted with COVID-19.

Methods: We retrospectively identified all patients with a positive test result for SARS-CoV-2 who were admitted to a large quaternary care center in New York City in spring 2020. Details of the patients' demographics and hospital course were obtained retrospectively from medical records. Patients were defined as having hypermagnesemia if their median magnesium over the course of their hospitalization was >2.4 mg/dl.

Results: A total of 1685 patients hospitalized with COVID-19 had their magnesium levels checked during their hospitalization, and were included in the final study cohort, among whom 355 (21%) had hypermagnesemia. Patients who were hypermagnesemic had a higher incidence of shock requiring pressors (35% vs 27%, P<0.01), respiratory failure requiring mechanical ventilation (28% vs 21%, P=0.01), AKI (65% vs 50%, P<0.001), and AKI severe enough to require renal replacement therapy (18% vs 5%, P<0.001). In an adjusted multivariable model, hypermagnesemia was observed more commonly with increasing age, male sex, AKI requiring RRT, hyperkalemia, and higher CPK. Survival probability at 30 days was 34% for the patients with hypermagnesemia, compared with 65% for patients without hypermagnesemia. An adjusted multivariable time to event analysis identified an increased risk of mortality with older age, need for vasopressors, higher C-reactive protein levels, and hypermagnesemia (HR, 2.03; 95% CI, 1.63 to 2.54, P<0.001).

Conclusions: In conclusion, we identified an association between hypermagnesemia among patients hospitalized with COVID-19 and increased mortality. Although the exact mechanism of this relationship remains unclear, hypermagnesemia potentially represents increased cell turnover and higher severity of illness, which is frequently associated with more severe forms of AKI.

Keywords: COVID-19; SARS-CoV-2; acid/base and electrolyte disorders; coronavirus; hypermagnesemia; magnesium; rhabdomyolysis.

Graphical abstract

Figure 1.

Incidence and outcomes of patients who are hypermagnesemic. Of the 1685 (59%) of patients with COVID-19 admitted who had magnesium levels checked, 21% had a median magnesium level >2.4 mg/dl. In total, 38% of patients with hypermagnesemia died during their hospitalization, compared with only 19% of patients without hypermagnesemia. Mg, magnesium; COVID-19, coronavirus disease 2019.

Figure 2.

Patient survival curves by hypermagnesemia status. Kaplan–Meier curve for patient survival over time from admission for all patients stratified by those who had a median magnesium less than the upper limit of normal (red) and those who had a median magnesium greater than the upper limit of normal (>2.4 mg/dl; blue), P<0.001. HyperMg, hypermagnesemia.