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

J Emerg Med. 2022 Sep;63(3):399-413. doi: 10.1016/j.jemermed.2022.06.007. Epub 2022 Oct 11.


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

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

Methods: 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.

Results: 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).

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

Keywords: electrolyte disorders; hypokalemia; magnesium; pharmacology; potassium.

MeSH terms

  • Adult
  • Emergency Service, Hospital
  • Humans
  • Hypokalemia* / chemically induced
  • Hypokalemia* / drug therapy
  • Magnesium / pharmacology
  • Magnesium / therapeutic use
  • Potassium
  • Retrospective Studies


  • Magnesium
  • Potassium