Department of General and Surgical Critical Care Medicine, Innsbruck Medical University Hospital, Anichstr. 35, 6020 Innsbruck, Austria.
Nutrients. 2020 Mar 15;12(3):774. doi: 10.3390/nu12030774.
Hypernatremia is common in critical care, especially in severely burned patients. Its occurrence has been linked to increased mortality. Causes of hypernatremia involve a net gain of sodium or a loss of free water. Renal loss of electrolyte-free water due to urea-induced osmotic diuresis has been described as causative in up to 10% of hypernatremic critical ill patients. In this context, excessive urea production due to protein catabolism acts as major contributor. In severe burn injury, muscle wasting occurs as result of hypermetabolism triggered by ongoing systemic inflammation. In this retrospective study, severely burned patients were analysed for the occurrence of hypernatremia and subsequent signs of hypermetabolism. The urea: creatinine ratio-as a surrogate for hypermetabolism-sufficiently discriminated between two groups. Four of nine hypernatremic burn patients (44%) had a highly elevated urea: creatinine ratio, which was clearly associated with an increased urea production and catabolic index. This hypermetabolism was linked to hypernatremia via an elevated urea- and reduced electrolyte-fraction in renal osmole excretion, which resulted in an increased renal loss of electrolyte-free water. In hypermetabolic severely burned patients, the electrolyte-free water clearance is a major contributor to hypernatremia. A positive correlation to serum sodium concentration was shown.
高钠血症在重症监护中很常见，特别是在严重烧伤患者中。其发生与死亡率增加有关。高钠血症的病因涉及钠的净增加或游离水的丢失。由于尿素诱导的渗透性利尿导致电解质自由水的肾丢失，已被描述为高达 10%的高钠血症重症患者的病因。在这种情况下，由于蛋白质分解代谢导致的过量尿素产生是主要原因。在严重烧伤中，由于持续的全身炎症引起的高代谢，肌肉消耗发生。在这项回顾性研究中，分析了严重烧伤患者高钠血症的发生情况以及随后的高代谢迹象。尿素：肌酐比值作为高代谢的替代指标，足以将两组区分开来。9 名高钠血症烧伤患者中有 4 名（44%）尿素：肌酐比值明显升高，这与尿素产生增加和分解代谢指数增加明显相关。这种高代谢通过肾脏渗透溶质排泄中升高的尿素和降低的电解质分数与高钠血症相关，导致电解质自由水的肾脏丢失增加。在高代谢性严重烧伤患者中，电解质自由水清除率是高钠血症的主要原因。结果显示与血清钠浓度呈正相关。
