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(mag-nē′zē-ŭm, -zhĕm )
[magnesia + -ium]
SYMB: Mg A white mineral element, atomic weight (mass) 24.312, atomic number 12, specific gravity 1.738. It is a naturally occurring element, abundant in sea water. Magnesium is found in soft tissue, muscles, bones, to some extent in body fluids, and is the second most common cation in intracellular fluid. The human body contains approx. 25 mg of magnesium, mostly in the bones. Muscles contain less magnesium than calcium. Concentration of magnesium in the serum is between 1.5 and 2.5 mmol/L.
Magnesium deficiency is rare because it is common in foods, e.g., fish, whole grains, fruits, and green vegetables. A typical diet contains 200 to 400 mg of magnesium, about one third of which is absorbed through the small intestine, the rest being excreted in the stool. The major function of magnesium is to enhance neuromuscular integration, but magnesium also stimulates secretion of parathyroid hormone, thus regulating intracellular fluid calcium levels.
Magnesium is needed for DNA repair. It moderates cellular differentiation and proliferation and improves tissue sensitivity to circulating insulin. It is a component of enzymes required for the synthesis of adenosine triphosphate (ATP) and the release of energy from ATP. It is also a component of enzymes involved in muscle contraction and protein synthesis.
CAS # 7439-95-4
Magnesium is often administered orally or parenterally to patients with asthma, constipation, preeclampsia, eclampsia, or torsades de pointes. Excessive oral intake (resulting in hypermagnesemia) may promote diarrhea (compounds containing magnesium are given as laxatives).
Hypermagnesemia (excess of magnesium in blood serum) is rare in patients with normal kidney function but may develop in patients taking magnesium supplementation for impaired renal function. It may cause slowing of the heart rate, low blood pressure, decreased level of consciousness, and muscle weakness or flaccid paralysis. Severe hypermagnesemia may cause cardiac arrest. Treatment for hypermagnesemia includes withholding magnesium, increasing fluid intake, and administering loop diuretics. Calcium gluconate 10% may be administered for temporary relief of symptoms in an emergency or for magnesium intoxication. Peritoneal dialysis or hemodialysis may be needed if renal function fails or excess magnesium cannot be eliminated.
Hypomagnesemia (deficiency of magnesium in blood serum) may cause hypokalemia, hypoparathyroidism, hypocalcemia, tetany, irritability, confusion, delusions, cardiac arrhythmias, and chronic diarrhea.
During treatment of magnesium disorders, careful monitoring is needed of serum electrolyte and fluid balance, vital signs, level of consciousness, flaccidity, clonus, and cardiac rhythm.