MAGNESIUM

Magnesium: serum and urinary.

Serum magnesium

Magnesium is an element that, although found in small proportions in the body (0.05% of total body weight), is of great structural and functional importance. About 1% is in plasma, 25% is protein bound, the rest remains in ionized Mg2+ form. In erythrocytes the amount of magnesium is appreciable, about 5.2 mEq/L. Together with Na+, K+ and Ca2+ ions, magnesium regulates neuromuscular excitability and the coagulation mechanisms. The actions of calcium and magnesium are closely linked, the deficiency of one of these elements significantly influencing the metabolism of the other. 

Biological reference range:

Newborns (2 - 4 days old): 1.5-2.2 mg/dL; children (5 months - 6 years old): 1.7-2.3 mg/dL; children (6 - 12 years old): 1.7-2.1 mg/dL; adults: 1.6-2.6 mg/dL. 

Urinary magnesium

Normally 95% of the amount of magnesium that is filtered at the glomerular level is reabsorbed tubularly, especially in the ascending portion of the Henle loop. Magnesium excretion controls the serum level of this element and is dependent on diet. Magnesium, along with calcium, is subject to the effects of parathyroid hormone.