Disorders of Magnesium: Hypermagnesemia
Hypermagnesemia, which is defined as serum [Mg2+] > 2.7 mg/dL, is not a common electrolyte disorder in individuals with normal renal function. As stated in Chap. 23, the kidney is able to maintain serum [Mg2+] within normal range by enhancing its excretion in situations of excess Mg2+ intake. Therefore, a decrease in glomerular filtration rate (GFR), as seen in chronic kidney disease, seems to be the most common cause of hypermagnesemia. The other major cause is an exogenous load of Mg2+. Excess intake of Mg2+ can occur when a patient with preeclampsia (a condition characterized by proteinuria and hypertension during third trimester of pregnancy) is treated with magnesium sulfate or when individuals take Mg2+-containing antacids or enemas. Infants born to mothers who were treated with magnesium for preeclampsia/eclampsia may develop hypermagnesemia. Elderly individuals are particularly susceptible to Mg2+ toxicity because of decreased renal function with aging and excessive use of Mg2+-containing medications and vitamins. Subjects with familial hypocalciuric hypercalcemia may have elevated Mg2+ levels. Acromegalics and patients with adrenal insufficiency may have hypermagnesemia. The various causes of hypermagnesemia are summarized in Table 25.1.
KeywordsHypermagnesemia Familial hypocalciuric hypercalcemia Causes of hypermagnesemia Clinical manifestations of hypermagnesemia Treatment of hypermagnesemia
- 1.Hruska KA, Levi M, Slatopolsky E. Disorders of phosphorus, calcium, and magnesium metabolism. In: Coffman TM, Falk RJ, Molitoris BA et al, Editors. Schrier’s diseases of the kidney, 9th edn. Philadelphia: Lippincott Williams & Wilkins; 2013, pp 2116–81.Google Scholar