Abstract 13409: Maintaining a High Total Serum Magnesium Level With Intravenous Magnesium Sulfate

Abstract

Introduction: Understanding how intravenous magnesium sulfate (MgSO4) administration affects total serum magnesium concentration (TsMg) is important in maintaining a target TsMg level in acute heart failure patients on loop diuretics. Hypothesis: Describe how TsMg changes after single dose of MgSO4 and estimate how often MgSO4 should be given to maintain TsMg above 2 mg/dL. Methods: We studied hospitalizations of veterans from the Veterans Health Administration (VHA) aged ≥ 65 without severe renal disease (EGFR > 15 cc/min per 1.73 m2) from 2013-2017 with a primary diagnosis of acute heart failure. We constructed linear and logistic mixed-effects models with values of TsMg at level 1, nested within dose, hospitalization, and patient. Results: There were 27,474 doses of intravenous MgSO4 administered in 16,139 hospitalizations to 13,439 unique veterans across 145 hospitals in the VHA. Veterans were elderly (mean age 76), 98% male, 72% non-Hispanic white. Mean TsMg was initially high and leveled off 24-48 hours after MgSO4 administration, with an average TsMg increase of 0.2 mg/dL regardless of dose administered (Figure) . The probability of maintaining a TsMg above 2.0 mg/dL just one day after MgSO4 ranged from 49-54% (Table) . Conclusions: TsMg is often targeted above 2.0 gm/dL, especially in the setting of arrhythmias or QT-prolonging medications. As MgSO4 is frequently administered in heart failure patients on diuretics, understanding that TsMg may be misleadingly elevated for the first 48 hours after MgSO4 is important. We recommend administering MgSO4 at least once per day if the goal TsMg level is ≥ 2.0 gm/dL.