Medication Summary
Treatment depends on the degree of hypermagnesemia and the presence of symptoms. In patients with mildly increased levels, the source of magnesium may simply be removed. In patients with higher concentrations of magnesium or severe symptoms, other treatments are necessary. Reserve calcium for patients with life-threatening symptoms, such as arrhythmias or severe respiratory depression.
Intravenous fluids
Class Summary
Dilution of the extracellular magnesium concentration is the rationale behind intravenous use. Fluids are used with diuretics to promote diuresis of magnesium by the kidneys.
0.9% sodium chloride (normal saline)
Isotonic fluid. Restores water and sodium chloride losses.
Diuretics
Class Summary
These agents increase renal excretion of magnesium.
Furosemide (Lasix)
Increases excretion of water by interfering with chloride-binding cotransport system, which inhibits sodium and chloride reabsorption in the ascending loop of Henle and distal renal tubule. Promotes loss of magnesium. Administer PO dose with food or milk to decrease stomach upset.
Calcium
Class Summary
Calcium directly antagonizes the effects of magnesium.
Calcium chloride (10% sol)
Moderates nerve and muscle performance by regulating action potential excitation threshold. Dose expressed in calcium chloride, not elemental calcium. 1 g calcium chloride contains 270 mg elemental calcium.
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(A) Magnesium reabsorption in the thick ascending limb of the loop of Henle. The driving force for the reabsorption against a concentration gradient is a lumen-positive voltage gradient generated by the reabsorption of NaCl. FHHNC = Familial hypomagnesemia with hypercalciuria and nephrocalcinosis. ADH = autosomal dominant hypocalcemia. FHH/NSHPT = Familial hypomagnesemia/neonatal severe hyperparathyroidism. (B) Magnesium reabsorption in the distal convoluted tubule. Active transcellular transport is mediated by an apical entry through a magnesium channel and a basolateral exit, presumably via a Na+/Mg2+ exchange mechanism. HSH = Hypomagnesemia with secondary hypocalcemia. GS = Gitelman syndrome. IDH = Isolated dominant hypomagnesemia. Source: Konrad M, Schlingmann KP, Gudermann T: Insights into the molecular nature of magnesium homeostasis. Am J Physiol Renal Physiol 2004; 286: F599-F605.
