Magnesium is the second more abundant intracellular cation of the human body after potassium, being essential in great number of enzymatic and metabolic processes.Is a cofactor of all the enzymatic reactions that involve the ATP and comprises of the membrane that maintains the electrical excitability ofthe muscular and nervous cells.A low magnesium level is found in malabsortion syndrome, diuretic oraminoglucoside therapy; hyperparathyroidism or diabetic acidosis.Elevated concentration of magnesium is found in uremia, chronic renal failure, glomerulonephritis, Addisons’s disease or intensive antiacid therapy.Clinical diagnosis should not be made on a single test result; it should integrate clinical and other laboratory data.