Last updated: July 6, 2023

CME information and disclosurestoggle arrow icon

To see contributor disclosures related to this article, hover over this reference: [1]

Physicians may earn CME/MOC credit by reading information in this article to address a clinical question, and then completing a brief evaluation, in which they will identify their question and report the impact of any information learned on their clinical practice.

AMBOSS designates this Internet point-of-care activity for a maximum of 0.5 AMA PRA Category 1 Credit(s)™. Physicians should claim only credit commensurate with the extent of their participation in the activity.

For answers to questions about AMBOSS CME, including how to redeem CME/MOC credit, see "Tips and Links" at the bottom of this article.

Summarytoggle arrow icon

Hypermagnesemia is an electrolyte disorder in which serum magnesium levels are above the reference range. The most common cause is renal insufficiency in combination with increased magnesium intake (e.g., from laxatives). Other causes include magnesium therapy, hypothyroidism, and rhabdomyolysis. Mild hypermagnesemia is often asymptomatic but higher magnesium levels (e.g., above 4–5 mg/dL) can cause neuromuscular, gastrointestinal, and cardiovascular symptoms, including ECG abnormalities. In very severe cases, hypermagnesemia can lead to cardiac arrest and death. Concomitant electrolyte imbalances (e.g., hypocalcemia) should be assessed, as they may worsen symptoms. The most important treatment step is the discontinuation of magnesium intake, which is sufficient for most asymptomatic or stable patients. Symptomatic patients may be treated with IV isotonic fluids, IV calcium, and loop diuretics. Acute dialysis should be considered in severe cases.

Definitiontoggle arrow icon

Hypermagnesemia is a serum magnesium concentration above 2.2–2.4 mg/dL (0.91–1.0 mmol/L). [2][3]

Etiologytoggle arrow icon

Renal insufficiency in combination with increased magnesium intake (e.g., from laxatives) is the most common cause of hypermagnesemia.

Clinical featurestoggle arrow icon

Mild hypermagnesemia is often asymptomatic; symptoms typically occur if magnesium levels are above 4–5 mg/dL. [2][4]

Because most of the total magnesium in the body is located intracellularly, serum magnesium levels may not accurately reflect total body magnesium levels, and symptoms may not correlate with specific serum levels. [2][6]

Very high magnesium levels (e.g., ≥ 10 mg/dL) may lead to respiratory failure, heart block, and/or cardiac arrest! [2]

Diagnosticstoggle arrow icon

Laboratory studies [2][6]

Hypocalcemia may worsen symptoms of hypermagnesemia because calcium usually antagonizes the effects of magnesium. [7]

ECG [2]

ECG changes are usually seen if magnesium levels are > 7 mg/dL. Findings are nonspecific and may include: [6]

Treatmenttoggle arrow icon

Stable and asymptomatic patients with normal renal function usually do not require medical therapy.

All patients [2][3][6]

Significant and/or symptomatic hypermagnesemia [2][3][6]

Prevention is key in hypermagnesemia. Caution should be used in all patients treated with magnesium-containing medication, especially those with renal insufficiency.

Referencestoggle arrow icon

  1. $Contributor Disclosures - Hypermagnesemia. None of the individuals in control of the content for this article reported relevant financial relationships with ineligible companies. For details, please review our full conflict of interest (COI) policy:.
  2. Jameson JL, Fauci AS, Kasper DL, Hauser SL, Longo DL, Loscalzo J. Harrison's Principles of Internal Medicine, Twentieth Edition (Vol.1 & Vol.2). McGraw-Hill Education / Medical ; 2018
  3. Walls R, Hockberger R, Gausche-Hill M, Erickson TB, Wilcox SR. Rosen's Emergency Medicine 10th edition- Concepts and Clinical Practice E-Book. Elsevier Health Sciences ; 2022
  4. Zoungas S, Patel A, Chalmers J, de Galan BE, Li Q, Billot L, Woodward M, Ninomiya T, Neal B, MacMahon S, Grobbee DE, Kengne AP, Marre M, Heller S; ADVANCE Collaborative Group. Severe Hypoglycemia and Risks of Vascular Events and Death. N Engl J Med. 2010; 363 (15): p.1410-1418.doi: 10.1056/nejmoa1003795 . | Open in Read by QxMD
  5. Qazi M, Qazi H, Nakhoul G, Provenzano LF. Causes of Hypermagnesaemia: A Literature Review. EMJ Nephrol. 2021: p.107-115.doi: 10.33590/emjnephrol/21-00033 . | Open in Read by QxMD
  6. Topf JM, Murray PT. Hypomagnesemia and Hypermagnesemia. Rev Endocr Metab Disord. 2003; 4 (2): p.195-206.doi: 10.1023/a:1022950321817 . | Open in Read by QxMD
  7. Swaminathan R. Magnesium metabolism and its disorders.. Clin Biochem Rev. 2003; 24 (2): p.47-66.
  8. Vanden Hoek TL, Morrison LJ, Shuster M, et al. Part 12: Cardiac Arrest in Special Situations: 2010 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care. Circulation. 2010; 122 (18_suppl_3): p.S829-S861.doi: 10.1161/circulationaha.110.971069 . | Open in Read by QxMD
  9. American Heart Association. 2005 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Part 10.1: Life-Threatening Electrolyte Abnormalities. Circulation. 2005; 112 (24_supplement).doi: 10.1161/circulationaha.105.166563 . | Open in Read by QxMD

Icon of a lock3 free articles remaining

You have 3 free member-only articles left this month. Sign up and get unlimited access.
 Evidence-based content, created and peer-reviewed by physicians. Read the disclaimer