What is hypomagnesemia?

Updated: Oct 30, 2020
  • Author: Tibor Fulop, MD, PhD, FACP, FASN; Chief Editor: Vecihi Batuman, MD, FASN  more...
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Hypomagnesemia—serum levels of magnesium levels below the usual reference range of 1.5 to 2.5 mg/dL—can result from decreased intake, redistribution of magnesium from the extracellular to the intracellular space, or increased renal or gastrointestinal loss. It can be acquired or hereditary. Despite the well-recognized importance of magnesium, low and high levels have been documented on routine laboratory tests (as opposed to physician-initiated magnesium assays) in ill patients. [1]  Consequently, magnesium has occasionally been called the "forgotten cation." [2, 3]

Symptomatic hypomagnesemia commonly presents as involvement of the cardiovascular system and the central and peripheral nervous systems. However, magnesium deficiency can result in disturbances in nearly every organ system and can cause potentially fatal complications (eg, ventricular arrhythmia, coronary artery vasospasm, sudden death). See Presentation.  

For the most part, the signs and symptoms of hypomagnesemia are reversible with magnesium replacement. Therapy can be oral for patients with mild symptoms or intravenous for patients with severe symptoms or those unable to tolerate oral administration. Sources of magnesium loss (eg, diuretic use) may also need to be addressed. See Treatment and Medication.

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