Approximately 60% of the body's magnesium is stored in the bones, with most of the remainder located within the cells of skeletal muscles and other tissues and organs. Only 1%–2% of total body magnesium is found in the extracellular fluid. Magnesium plays a variety of physiological roles, including regulating the currents of various ion channels, acting as a catalyst for numerous enzymatic reactions, particularly those involved in adenosine triphosphate (ATP) metabolism, and contributing to processes such as cell growth regulation. It is also essential for maintaining the excitability of cardiac muscle, skeletal muscle, and gastrointestinal smooth muscle.
The normal serum magnesium concentration ranges between 0.75 and 1.25 mmol/L. Under normal circumstances, magnesium balance in the body is primarily regulated by the kidneys.
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