Department of Endocrinology, Diabetology and Metabolism, University Hospital of Basel, University of Basel, Petersgraben 4, 4031, Basel, Switzerland.
Medical Department III-Endocrinology, Nephrology, Rheumatology, University of Leipzig Medical Center, University Hospital Leipzig, Leipzig, Germany.
J Endocrinol Invest. 2020 Jan;43(1):21-30. doi: 10.1007/s40618-019-01087-6. Epub 2019 Jul 31.
Copeptin is secreted in equimolar amount to Arginine Vasopressin (AVP) but can easily be measured with a sandwich immunoassay. Both peptides, copeptin and AVP, show a high correlation. Accordingly, copeptin mirrors the amount of AVP in the circulation and its measurement provides an attractive marker in the differential diagnosis of diabetes insipidus.
Diabetes insipidus-either central or nephrogenic-has to be differentiated from primary polydipsia. Differentiation is crucial since wrong treatment can have deleterious consequences. Since many decades, the "gold standard" for differential diagnosis has been the classical water deprivation test, which has several limitations leading to an overall limited diagnostic accuracy. In addition, the test has a long duration of 17 hours and is cumbersome for patients. Clinical signs and symptoms as well as MRI characteristics overlap between patients with diabetes insipidus and primary polydipsia. Direct measurement of AVP upon osmotic stimulation was first shown to overcome these limitations, but failed to enter clinical practice mainly due to technical limitations of the AVP assay.
We have recently shown that copeptin, without prior water deprivation, identifies patients with nephrogenic diabetes insipidus. On the other hand, for the more difficult differentiation between central diabetes insipidus and primary polydipsia, a copeptin level of 4.9 pmol/L stimulated with hypertonic saline infusion differentiates between these two entities with a high diagnostic accuracy, and is superior to the water deprivation test. It is important to note that close sodium monitoring during the hypertonic saline test is a prerequisite.
Therefore, we propose that copeptin upon hypertonic saline infusion should become the new standard test in the differential diagnosis of diabetes insipidus.
加压素原与精氨酸加压素（AVP）以等摩尔量分泌，但可以通过夹心免疫测定法轻松测量。这两种肽，加压素原和 AVP，显示出高度相关性。因此，加压素原反映了循环中 AVP 的量，其测量为尿崩症的鉴别诊断提供了有吸引力的标志物。
尿崩症 - 无论是中枢性还是肾性 - 都需要与原发性多尿症区分开来。区分是至关重要的，因为错误的治疗可能会产生有害的后果。几十年来，鉴别诊断的“金标准”一直是经典的禁水试验，该试验具有导致整体诊断准确性有限的几个局限性。此外，该测试持续时间长达 17 小时，对患者来说很麻烦。尿崩症和原发性多尿症患者的临床症状和体征以及 MRI 特征重叠。渗透刺激后直接测量 AVP 首先被证明可以克服这些限制，但由于 AVP 测定的技术限制，未能进入临床实践。
我们最近表明，加压素原无需预先禁水即可识别肾性尿崩症患者。另一方面，对于更难区分中枢性尿崩症和原发性多尿症，在高渗盐水输注刺激下，4.9 pmol/L 的加压素原水平可区分这两种情况，具有较高的诊断准确性，并且优于禁水试验。重要的是要注意，在高渗盐水试验期间密切监测钠是前提。
因此，我们建议在鉴别诊断尿崩症时，应将高渗盐水输注后的加压素原作为新的标准试验。
