Magnesium Disorders:  Hypermagnesemia And Hypomagnesemia

Magnesium is involved in several physiological processes, including neuromuscular function, enzyme activity, and energy metabolism.  The normal serum magnesium concentration range is approximately 1.5 mg/dL to 2 mg/dL.  Hypermagnesemia and hypomagnesemia require prompt recognition and management to prevent potentially serious complications.

The human body contains about 2,000 mEq of magnesium with approximately 99% stored intracellularly or within bone; only 1% is present in the extracellular fluid.

Magnesium homeostasis is maintained through a delicate balance involving several factors.

Approximately 50%-60% of total body magnesium is stored in the bones, which serve as a reservoir for maintaining serum levels.

The kidneys are the primary regulators of magnesium balance.  Unlike most other solutes, the proximal tubule reabsorbs only 10% of filtered magnesium.  The majority (50%-70%) is passively reabsorbed in the thick ascending limb, with most of the remaining magnesium reabsorbed more distally.  Only 3%-5% of filtered magnesium is normally excreted in urine.