Kelepouris E, Agus Z S
Renal Electrolyte Division, Hospital of the University of Pennsylvania, University of Pennsylvania School of Medicine, Philadelphia, USA.
Semin Nephrol. 1998 Jan;18(1):58-73.
Magnesium is an important constituent of the intracellular space that affects a number of intracellular and whole body functions. Magnesium balance depends on intake and renal excretion, which is regulated mainly in the thick ascending limb of the loop of Henle. The complex hormonal modulation that responds to changes in plasma concentration of other ions such as calcium and potassium is lacking for magnesium. As a result, negative magnesium balance results in a prompt decrease in plasma magnesium concentration, and hypermagnesemia accompanies renal failure with magnesium accumulation. Hypomagnesemia may result from gastrointestinal losses or renal losses, the latter due to primary renal magnesium wasting or in association with sodium loss. Hypomagnesemia may arise together with and contribute to the persistence of hypokalemia and hypocalcemia. The major direct toxicity of hypomagnesemia is cardiovascular. When urgent correction of hypomagnesemia is required, as with myocardial ischemia, post cardiopulmonary bypass, and torsades de pointes, intravenous or intramuscular magnesium sulfate should be used. Oral magnesium preparations are available for chronic use.
镁是细胞内液的重要组成部分，影响多种细胞内和全身功能。镁平衡取决于摄入和肾脏排泄，肾脏排泄主要在髓袢升支粗段进行调节。镁缺乏对其他离子（如钙和钾）血浆浓度变化作出反应的复杂激素调节。因此，负镁平衡会导致血浆镁浓度迅速下降，而高镁血症则伴随肾衰竭和镁蓄积。低镁血症可能由胃肠道丢失或肾脏丢失引起，后者是由于原发性肾脏镁流失或与钠丢失有关。低镁血症可能与低钾血症和低钙血症同时出现并导致其持续存在。低镁血症的主要直接毒性是心血管方面的。当需要紧急纠正低镁血症时，如在心肌缺血、体外循环后和尖端扭转型室速时，应使用静脉或肌肉注射硫酸镁。口服镁制剂可用于长期治疗。
