The Effects of Magnesium Coadminstration During Treatment of Hypokalemia in the Emergency Department

Hypokalemia is a common disorder that can negatively affect organ function. Magnesium supplementation is frequently recommended despite limited evidence to support its use.

The purpose of this study was to evaluate the clinical effects of magnesium coadministration in patients treated for hypokalemia in the emergency department (ED).

This retrospective, single-center study evaluated adults treated with intravenous (i.v.) potassium for hypokalemia (serum potassium <3.5 mMol/L) in the ED between July 1, 2016 and June 30, 2020. Patients given magnesium supplementation within 4 h of potassium administration (MG+) were compared with those not given concurrent magnesium (MG-). The primary outcome was time to potassium normalization (≥ 3.5 mMol/L). Secondary outcomes included clinical effects, adverse effects, and dosing of magnesium and potassium.

Two hundred patients were included (MG+ = 100; MG- = 100). Patients in the MG- group more frequently had history of myocardial infarction (16% vs. 6%; p = 0.02) and alcoholism (16% vs. 6%; p = 0.02). Patients in the MG+ group had higher incidence of symptomatic hypokalemia (34% vs. 19%; p = 0.02) and severe hypokalemia (serum potassium < 2.5 mMol/L) (15% vs. 8%; p = 0.03). There were no differences in time to serum potassium normalization, change in serum potassium after treatment, or incidence of potassium normalization within 24 h of treatment. MG+ patients required more potassium within 24 h of treatment and more frequently developed hypermagnesemia (serum magnesium >1.1 mMol/L).

Magnesium coadministration during hypokalemia treatment did not affect time to serum potassium normalization but was associated with more hypermagnesemia.