Contributor: Dylan Luyten, MD

Educational Pearls:

• Those that are hypokalemic are often hypomagnesemic, and should receive magnesium (Mg) supplementation if repleting potassium
• Mg levels are typically not necessary - if someone is suspect to have hypomagnesemia, just given them Mg
• Mg increases the AV node refractory period and therefore may be helpful as an adjunct to those in atrial fibrillation with a rapid ventricular response
• Mg is the preferred treatment for seizure prophylaxis in preeclampsia. All patients with suspected preeclampsia should get 4g Mg IV over 20 min
• Mg may reduce hospital admissions in those with severe asthma, though it has not shown to have mortality or other benefits in acute exacerbations

Editor's note: and we didn't even touch on magnesium in headaches

References

Huang CL, Kuo E. Mechanism of hypokalemia in magnesium deficiency. J Am Soc Nephrol. 2007 Oct;18(10):2649-52. doi: 10.1681/ASN.2007070792. Epub 2007 Sep 5. Review. PubMed PMID: 17804670.

Ismail Y, Ismail AA, Ismail AA. The underestimated problem of using serum magnesium measurements to exclude magnesium deficiency in adults; a health warning is needed for "normal" results. Clin Chem Lab Med. 2010 Mar;48(3):323-7. doi: 10.1515/CCLM.2010.077. PubMed PMID: 20170394.

Heitz C, Morgenstern J, Bond C, Milne WK. Hot Off the Press: Low-dose Magnesium Sulfate Versus High Dose in the Early Management of Rapid Atrial Fibrillation: Randomized Controlled Double-blind Study. Acad Emerg Med. 2019 Sep;26(9):1093-1095. doi: 10.1111/acem.13720. Epub 2019 Mar 18. PubMed PMID: 30815951.

Levy Z, Slesinger TL. Does intravenous magnesium reduce the need for hospital admission among adult patients with acute asthma exacerbations?. Ann Emerg Med.2015 Jun;65(6):702-3. doi: 10.1016/j.annemergmed.2014.07.019. Epub 2014 Aug 13. PubMed PMID: 25128007.

Summarized by Will Dewispelaere, MS4 | Edited by Erik Verzemnieks, MD