This test is used to evaluate magnesium levels. Decreased levels of magnesium have been associated with cardiac arrhythmias. Magnesium deficiency produces neuromuscular disorders causing weakness, tremors, tetany, and convulsions. Hypomagnesemia is associated with hypocalcemia, hypokalemia, long-term hyperalimentation, intravenous therapy, diabetes mellitus, especially during treatment of ketoacidosis; alcoholism and other types of malnutrition; malabsorption; hyperparathyroidism; dialysis; pregnancy; and hyperaldosteronism. Renal loss of magnesium occurs with cis-platinum therapy. Increased magnesium levels relate mostly to individuals in renal failure. Marked increases may be found in such individuals who take magnesium salts (eg, as antacids which contain magnesium). Increased serum magnesium is also found with Addison disease and in pregnant woman with severe pre-eclampsia or eclampsia who are receiving magnesium sulfate as an anticonvulsant. Hypermagnesemia may occur in individuals using magnesium-containing cathartics. High magnesium levels are manifested by decreased reflexes, somnolence, and heart block.