Decaux G, Prospert F, Namias B, Soupart A
Unité de Recherche du Métabolisme Hydrominéral, Hôpital Universitaire Erasme, Université Libre de Bruxelles, Brussels, Belgium.
Am J Med. 1997 Nov;103(5):376-82. doi: 10.1016/s0002-9343(97)00165-4.
In the differential diagnosis of patients with polyuria-polydipsia one must distinguish usually between primary polydipsia (PP) and central diabetes insipidus (CDI). The first situation is a state of volume expansion and the second of volume contraction. We evaluate whether serum uric acid determination could help to differentiate between the two conditions.
We analyzed the score of 13 consecutive patients with CDI, 7 patients with PP, and 7 patients with nephrogenic diabetes insipidus (NDI). Serum uric acid concentration was available during normonatremia without treatment with 1-desamino-8-D-arginine vasopressin (dDAVP), during mild dehydration and during treatment with dDAVP. In 8 of these patients plasma renin activity (PRA), urate, urea and creatinine clearances were also available. These data were also obtained in the patients with NDI. In 1 patient with CDI, we studied the effect on urate clearance of dDAVP, which stimulates exclusively the V2 receptors, and of triglycyl-lysine-vasopressin (TGLV), a potent V1-receptor agonist.
Normonatremic polydypsic patients with CDI presented an increase in uric acid concentration (7.1 +/- 2.2 mg/dL), whereas in the PP group the value was decreased (3 +/- 0.75 mg/dL; P <0.001). All the normonatremic PP presented a serum uric acid concentration lower than 5 mg/dL, whereas all the normonatremic CDI patients, exept 1, presented a value higher than 5 mg/dL. In both groups blood urea concentration was decreased as a consequence of high renal clearances. The hyperuricemia of CDI was related to low uric acid clearances. Patients with hypernatremia and NDI presented a lower increase in serum uric acid concentration than those with similar levels of hypernatremia and CDI (NDI: 5.7 +/- 0.8 mg/dL and CDI: 7.9 +/- 2.3 mg/dL; P <0.05) and the NDI patients presented an urate clearance corrected for creatinine clearance which was significantly higher than in CDI (9% +/- 3% and 4% +/- 1.1%; P <0.01). When the patients with CDI were treated with dDAVP and normalyzed their PRA (0.9 +/- 0.4 ng/mL/h) we observed still mild hyperuricemia compared to controls (5.5 +/- 1.4 mg/dL and 4.3 +/- 0.9 mg/dL; P <0.01) and a low fractional excretion of filtered uric acid (6.5% +/- 1.7% compared to 8.2% +/- 2% in controls; P <0.05). Acute administration of dDAVP, stimulating the V2 receptors, in one patient with CDI, had no effect on urate clerance, while TGLV, which stimulates the V1 receptor, increased urate clearance.
The presence of an serum uric acid concentration higher than 5 mg/dL in polyuric polydipsic patients is highly suggestive of CDI. Even when these patients are treated with dDAVP many of them remain hyperuricemic, and this seems to be the consequence of a lack of V1 receptor stimulation.
在多尿-多饮患者的鉴别诊断中，通常必须区分原发性烦渴（PP）和中枢性尿崩症（CDI）。第一种情况是容量扩张状态，第二种是容量收缩状态。我们评估血清尿酸测定是否有助于区分这两种情况。
我们分析了13例连续的CDI患者、7例PP患者和7例肾性尿崩症（NDI）患者的情况。在血钠正常且未用1-去氨基-8-D-精氨酸加压素（dDAVP）治疗时、轻度脱水时以及dDAVP治疗期间，均可获得血清尿酸浓度。在这些患者中的8例中，还可获得血浆肾素活性（PRA）、尿酸、尿素和肌酐清除率。这些数据也在NDI患者中获得。在1例CDI患者中，我们研究了仅刺激V2受体的dDAVP以及强效V1受体激动剂三甘氨酰赖氨酸加压素（TGLV）对尿酸清除率的影响。
血钠正常的CDI多饮患者尿酸浓度升高（7.1±2.2mg/dL），而PP组的值降低（3±0.75mg/dL；P<0.001）。所有血钠正常的PP患者血清尿酸浓度均低于5mg/dL，而除1例之外的所有血钠正常的CDI患者的值均高于5mg/dL。由于高肾清除率，两组的血尿素浓度均降低。CDI的高尿酸血症与低尿酸清除率有关。高钠血症和NDI患者血清尿酸浓度的升高低于具有相似高钠血症水平的CDI患者（NDI：5.7±0.8mg/dL，CDI：7.9±2.3mg/dL；P<0.05），并且NDI患者经肌酐清除率校正后的尿酸清除率显著高于CDI（9%±3%和4%±1.1%；P<0.01）。当CDI患者用dDAVP治疗并使其PRA正常化（0.9±0.4ng/mL/h）时，与对照组相比，我们仍观察到轻度高尿酸血症（5.5±1.4mg/dL和4.3±0.9mg/dL；P<0.0１）以及低滤过尿酸排泄分数（6.5%±1.7%，而对照组为8.2%±2%；P<0.05）。在1例CDI患者中急性给予刺激V2受体的dDAVP对尿酸清除率无影响，而刺激V1受体的TGLV可增加尿酸清除率。
多尿多饮患者血清尿酸浓度高于5mg/dL高度提示CDI。即使这些患者用dDAVP治疗，他们中的许多人仍保持高尿酸血症，这似乎是缺乏V1受体刺激的结果。
