[The clinical importance of magnesium. 2. The indications for supplementation and therapy].

Mg deficiency is characterized by diverse secondary electrolyte alterations. Extracellularly, hypocalcemia is a particular feature, which may be explained by increased resistance of bone towards parathormone. Intracellularly, decreased concentrations of Mg and K and increased amounts of Na and Ca are found in contractile organelles. At increased Mg levels, concentration of parathormone may decrease, leading to hypocalcemia. Calcium-antagonistic effects are observed in smooth muscle, the myocardium and the end-plate of skeletal muscles. Hence, Mg may be prescribed either to correct a deficit or to utilize its pharmacologic effects. Dosaging still needs to be optimized.