Official reprint from UpToDate®
www.uptodate.com ©2016 UpToDate®

Causes and treatment of hypermagnesemia

Alan S L Yu, MB, BChir
Aditi Gupta, MD
Section Editor
Stanley Goldfarb, MD
Deputy Editor
Albert Q Lam, MD


The kidney is crucial in maintaining the normal plasma magnesium concentration in the narrow range of 0.7 to 1.1 mmol/L. In contrast to most other filtered solutes, only 10 percent of filtered magnesium is absorbed in the proximal tubule; most (50 to 70 percent) of the filtered magnesium is passively reabsorbed in the cortical aspect of the thick ascending limb of Henle [1,2]. Magnesium reabsorption at this site is paracellular and voltage dependent, mediated by the tight junction proteins, claudin-16 and claudin-19. Loop reabsorption is appropriately diminished with magnesium loading, thereby allowing the excess magnesium to be excreted in the urine [1].

The causes and treatment of hypermagnesemia are reviewed in this topic. The symptoms of hypermagnesemia, the normal regulation of magnesium balance, and the different units used to measure the plasma magnesium concentration are discussed separately. (See "Symptoms of hypermagnesemia" and "Regulation of magnesium balance".)


The efficiency of the renal response to a magnesium load is such that hypermagnesemia is primarily seen in two settings: when renal function is impaired and/or when a large magnesium load is given, whether intravenously, orally, or as an enema.

Renal insufficiency — Hypermagnesemia can be seen in 10 to 15 percent of hospitalized patients, usually in the setting of renal failure. Plasma magnesium levels rise as renal function declines since there is no magnesium regulatory system other than urinary excretion. The typical patient with end-stage renal disease (ESRD), for example, has a plasma magnesium concentration of 2 to 3 meq/L (2.4 to 3.6 mg/dL or 1 to 1.5 mmol/L). In patients on dialysis, the plasma magnesium concentration is primarily determined by magnesium intake. This was shown in a cross-sectional study of patients on hemodialysis who completed a dietary questionnaire; the correlation between estimated dietary magnesium intake and the serum magnesium was 0.87 [3]. In addition, hypermagnesemia (defined as a serum magnesium greater than 1.5 mmol/L) occurred with magnesium intakes as low as 281 mg/day, which is considerably lower than the average intake in the general population. Severe and symptomatic hypermagnesemia can also be induced when exogenous magnesium is given as antacids or laxatives in usual therapeutic doses [4]. As a result, these drugs are contraindicated in patients with renal impairment.

Magnesium infusion — Parenteral magnesium is commonly used to decrease neuromuscular excitability in pregnant women with severe preeclampsia or eclampsia. The usual plasma concentration achieved is 5 to 7 meq/L (6 to 8.4 mg/dL or 2.5 to 3.5 mmol/L), but much higher levels can occur. There are few prospective studies of complications associated with this regimen, but maternal hypocalcemia (since hypermagnesemia can suppress the release of parathyroid hormone) and hyperkalemia have been described, as have neonatal hypocalcemia, hypotonia, osteopenia, and an increased rate of admissions to the neonatal intensive care unit [5-10]. (See "Symptoms of hypermagnesemia".)


Subscribers log in here

To continue reading this article, you must log in with your personal, hospital, or group practice subscription. For more information or to purchase a personal subscription, click below on the option that best describes you:
Literature review current through: Sep 2016. | This topic last updated: Apr 23, 2015.
The content on the UpToDate website is not intended nor recommended as a substitute for medical advice, diagnosis, or treatment. Always seek the advice of your own physician or other qualified health care professional regarding any medical questions or conditions. The use of this website is governed by the UpToDate Terms of Use ©2016 UpToDate, Inc.
  1. Quamme GA. Control of magnesium transport in the thick ascending limb. Am J Physiol 1989; 256:F197.
  2. Dai LJ, Quamme GA. Intracellular Mg2+ and magnesium depletion in isolated renal thick ascending limb cells. J Clin Invest 1991; 88:1255.
  3. Wyskida K, Witkowicz J, Chudek J, Więcek A. Daily magnesium intake and hypermagnesemia in hemodialysis patients with chronic kidney disease. J Ren Nutr 2012; 22:19.
  5. Monif GR, Savory J. Iatrogenic maternal hypocalcemia following magnesium sulfate therapy. JAMA 1972; 219:1469.
  6. Donovan EF, Tsang RC, Steichen JJ, et al. Neonatal hypermagnesemia: effect on parathyroid hormone and calcium homeostasis. J Pediatr 1980; 96:305.
  7. Rasch DK, Huber PA, Richardson CJ, et al. Neurobehavioral effects of neonatal hypermagnesemia. J Pediatr 1982; 100:272.
  8. Kaplan W, Haymond MW, McKay S, Karaviti LP. Osteopenic effects of MgSO4 in multiple pregnancies. J Pediatr Endocrinol Metab 2006; 19:1225.
  9. Greenberg MB, Penn AA, Whitaker KR, et al. Effect of magnesium sulfate exposure on term neonates. J Perinatol 2013; 33:188.
  10. Abbassi-Ghanavati M, Alexander JM, McIntire DD, et al. Neonatal effects of magnesium sulfate given to the mother. Am J Perinatol 2012; 29:795.
  11. Castelbaum AR, Donofrio PD, Walker FO, Troost BT. Laxative abuse causing hypermagnesemia, quadriparesis, and neuromuscular junction defect. Neurology 1989; 39:746.
  12. Woodard JA, Shannon M, Lacouture PG, Woolf A. Serum magnesium concentrations after repetitive magnesium cathartic administration. Am J Emerg Med 1990; 8:297.
  13. Gren J, Woolf A. Hypermagnesemia associated with catharsis in a salicylate-intoxicated patient with anorexia nervosa. Ann Emerg Med 1989; 18:200.
  14. Weber CA, Santiago RM. Hypermagnesemia. A potential complication during treatment of theophylline intoxication with oral activated charcoal and magnesium-containing cathartics. Chest 1989; 95:56.
  15. Birrer RB, Shallash AJ, Totten V. Hypermagnesemia-induced fatality following epsom salt gargles(1). J Emerg Med 2002; 22:185.
  16. Clark BA, Brown RS. Unsuspected morbid hypermagnesemia in elderly patients. Am J Nephrol 1992; 12:336.
  17. Weng YM, Chen SY, Chen HC, et al. Hypermagnesemia in a constipated female. J Emerg Med 2013; 44:e57.
  18. Porath A, Mosseri M, Harman I, et al. Dead Sea water poisoning. Ann Emerg Med 1989; 18:187.
  19. Schelling JR. Fatal hypermagnesemia. Clin Nephrol 2000; 53:61.
  20. Mordes JP, Wacker WE. Excess magnesium. Pharmacol Rev 1977; 29:273.