Last updated: March 8, 2021
Hypomagnesemia (low serum magnesium) is very common in critically unwell patients but can occur in the community, particularly secondary to medication use. Magnesium has a vital role in membrane stabilization and while the symptoms of mild deficiency can be nonspecific, severe hypomagnesemia can cause serious complications, such as cardiac arrhythmias and seizures. Hypomagnesemia is commonly seen alongside other electrolyte abnormalities, and magnesium levels should always be checked in patients with hypokalemia or hypocalcemia. Management consists of magnesium replacement, treatment of associated electrolyte imbalances, and addressing the underlying causes.
- Serum magnesium concentration < 1.5 mEq/dL 
- Severe hypomagnesemia: magnesium concentration < 1.0 mEq/dL 
|Causes of hypomagnesemia |
| || Causes 
| Renal || |
- Congenital conditions
|Cell shifts ||
Low body magnesium stores can affect many organ systems. The presence and severity of symptoms do not always correlate with serum magnesium levels. 
Gastrointestinal: anorexia, nausea, vomiting
Parenteral administration of magnesium can reduce serum calcium levels, which can worsen preexisting hypocalcemia.
We list the most important complications. The selection is not exhaustive.
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Accessed: December 6, 2019.
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