Department of Endocrinology, Diabetology and Metabolism, University Hospital Basel, Basel, Switzerland.
University of Basel, Basel, Switzerland.
Clin Endocrinol (Oxf). 2019 Jul;91(1):22-32. doi: 10.1111/cen.13991. Epub 2019 May 8.
Copeptin is secreted in an equimolar amount to arginine vasopressin (AVP) but can easily be measured in plasma or serum with a sandwich immunoassay. The main stimuli for copeptin are similar to AVP, that is an increase in osmolality and a decrease in arterial blood volume and pressure. A high correlation between copeptin and AVP has been shown. Accordingly, copeptin mirrors the amount of AVP in the circulation. Copeptin has, therefore, been evaluated as diagnostic biomarker in vasopressin-dependent disorders of body fluid homeostasis. Disorders of body fluid homeostasis are common and can be divided into hyper- and hypoosmolar circumstances: the classical hyperosmolar disorder is diabetes insipidus, while the most common hypoosmolar disorder is the syndrome of inappropriate antidiuresis (SIAD). Copeptin measurement has led to a "revival" of the direct test in the differential diagnosis of diabetes insipidus. Baseline copeptin levels, without prior thirsting, unequivocally identify patients with nephrogenic diabetes insipidus. In contrast, for the difficult differentiation between central diabetes insipidus and primary polydipsia, a stimulated copeptin level of 4.9 pmol/L upon hypertonic saline infusion differentiates these two entities with a high diagnostic accuracy and is clearly superior to the classical water deprivation test. On the contrary, in the SIAD, copeptin measurement is of only little diagnostic value. Copeptin levels widely overlap in patients with hyponatraemia and emphasize the heterogeneity of the disease. Additionally, a variety of factors lead to unspecific copeptin elevations in the acute setting further complicating its interpretation. The broad use of copeptin as diagnostic marker in hyponatraemia and specifically to detect cancer-related disease in SIADH patients can, therefore, not be recommended.
copeptin 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血浆或血清中的 copeptin。copeptin 的主要刺激因素与 AVP 相似，即渗透压升高和动脉血容量和血压降低。已经证明 copeptin 与 AVP 之间具有高度相关性。因此，copeptin 反映了循环中 AVP 的量。因此，copeptin 已被评估为与血管加压素依赖性体液稳态紊乱相关的诊断生物标志物。体液稳态紊乱很常见，可以分为高渗和低渗情况：经典的高渗紊乱是尿崩症，而最常见的低渗紊乱是抗利尿激素分泌不当综合征（SIAD）。copeptin 测量导致了尿崩症鉴别诊断中直接测试的“复兴”。在没有先前口渴的情况下，基线 copeptin 水平明确识别出肾性尿崩症患者。相比之下，对于中枢性尿崩症和原发性多尿症的困难鉴别，在高渗盐水输注后激发的 copeptin 水平 4.9 pmol/L 可区分这两种实体，具有较高的诊断准确性，明显优于经典的限水试验。相反，在 SIAD 中，copeptin 测量的诊断价值很小。低钠血症患者的 copeptin 水平广泛重叠，强调了该疾病的异质性。此外，各种因素导致急性情况下 copeptin 非特异性升高，进一步使它的解释复杂化。因此，不能推荐广泛将 copeptin 作为低钠血症的诊断标志物，特别是在 SIADH 患者中用于检测癌症相关疾病。
