Freeman J B, Wittine M F, Stegink L D, Mason E D
Can J Surg. 1982 Sep;25(5):570-2, 574.
The effects of magnesium infusions on urinary and fecal magnesium excretion, serum magnesium and nitrogen balance were examined in seven well-nourished and three nutritionally depleted adult surgical patients receiving total parenteral nutrition. They were maintained on constant nitrogen and caloric intake for 14 +/- 2 days. Magnesium doses ranged from 0 to 664 mg/d and were given in varying crossover patterns. In both groups, urinary magnesium excretion increased as the amount of magnesium infused increased but, at comparable magnesium infusions, depleted patients excreted significantly less magnesium. Renal conservation was most pronounced in well-nourished patients on magnesium-free intake and in depleted patients given 70 mg magnesium daily. Urinary magnesium losses were 40 +/- 5 mg/d and 33 +/- 8 mg/d, respectively, in these two groups. Endogenous fecal magnesium excretion was minimal and ranged from 2 to 38 mg/d. At each level of magnesium intake, serum levels of well-nourished patients were normal. With infusions of less than 200 mg/d, serum magnesium concentrations in depleted subjects averaged 1.6 mg/dl. Reduced urinary magnesium excretion as well as borderline serum levels measured in depleted adults suggest that the magnesium dosage should be higher than that usually recommended during total parenteral nutrition. In both groups a positive correlation between magnesium and nitrogen balance was noted.
在7名营养良好和3名营养缺乏的接受全胃肠外营养的成年外科患者中，研究了输注镁对尿镁和粪镁排泄、血清镁及氮平衡的影响。他们在14±2天内保持恒定的氮和热量摄入。镁剂量范围为0至664mg/d，并以不同的交叉方式给予。在两组中，尿镁排泄量均随镁输注量的增加而增加，但在输注量相当的情况下，营养缺乏患者排泄的镁明显较少。肾脏保留在无镁摄入的营养良好患者和每天给予70mg镁的营养缺乏患者中最为明显。这两组患者的尿镁丢失量分别为40±5mg/d和33±8mg/d。内源性粪镁排泄极少，范围为2至38mg/d。在每个镁摄入水平，营养良好患者的血清水平均正常。当输注量低于200mg/d时，营养缺乏受试者的血清镁浓度平均为1.6mg/dl。营养缺乏成年人中尿镁排泄减少以及血清水平处于临界状态，这表明在全胃肠外营养期间，镁的剂量应高于通常推荐的剂量。在两组中，均观察到镁与氮平衡之间呈正相关。
