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