Comtois R, Bertrand S, Beauregard H, Vinay P
Département de médecine, hôpital Notre-Dame, Université de Montréal, Québec, Canada.
Union Med Can. 1990 Nov-Dec;119(6):317-21.
Dehydrated patients usually present with an elevated serum urea level, owing in part to increased renal reabsorption of urea mediated by antidiuretic hormone (ADH). This study was carried out in order to examine whether, during dehydration, the variations in the serum urea level could discriminate patients with central diabetes insipidus (CDI) from those with dehydration due to other causes. We studied retrospectively 27 episodes of dehydration in 23 patients with CDI and 14 episodes in 14 patients without CDI. The mean serum urea level was 2.9 mmol/L in the CDI group and 15.4 mmol/L in the patients without CDI (p less than 0.001) while the mean serum sodium level was 155 mmol/L in both groups. During dehydration, patients with CDI decreased their serum urea level (4.0 +/- 2.3 vs 2.9 +/- 1.5 mmol/L, p less than 0.001). In addition, a positive correlation was found in the patients with CDI between the magnitude of diuresis and the percentage decrease in the serum urea level compared with the level before dehydration (r = 0.70, p less than 0.001). A striking increase in the clearance of urea (0.8 +/- 1 vs 2.1 +/- 1 ml/s, P less than 0.01), which exceeded the creatinine clearance (1.8 +/- 0.5 ml/s), was observed during dehydration in the six patients in whom clearance studies were done. Therefore, our results suggest that serum urea values can be used to distinguish patients dehydrated because of CDI from those with hypertonic dehydration but without ADH deficiency and that during dehydration the reabsorption of urea is mainly dependent on the renal action of ADH.
脱水患者通常表现出血清尿素水平升高，部分原因是抗利尿激素（ADH）介导的肾脏对尿素的重吸收增加。本研究旨在探讨在脱水过程中，血清尿素水平的变化是否能够区分中枢性尿崩症（CDI）患者与其他原因导致的脱水患者。我们回顾性研究了23例CDI患者的27次脱水发作以及14例非CDI患者的14次脱水发作。CDI组的平均血清尿素水平为2.9 mmol/L，非CDI患者为15.4 mmol/L（p<0.001），而两组的平均血清钠水平均为155 mmol/L。在脱水过程中，CDI患者的血清尿素水平下降（4.0±2.3 vs 2.9±1.5 mmol/L，p<0.001）。此外，在CDI患者中，发现利尿幅度与脱水前血清尿素水平相比的下降百分比之间存在正相关（r=0.70，p<0.001）。在进行清除率研究的6例患者中，脱水期间观察到尿素清除率显著增加（0.8±1 vs 2.1±1 ml/s，P<0.01），超过了肌酐清除率（1.8±0.5 ml/s）。因此，我们的结果表明，血清尿素值可用于区分因CDI导致脱水的患者与高渗性脱水但无ADH缺乏的患者，并且在脱水期间尿素的重吸收主要取决于ADH的肾脏作用。
