PDF(Pubmed)
Abstract：
The syndrome of inappropriate antidiuretic hormone secretion (SIADH) is frequent in lung cancer patients. Here, we report a case with persistent hyponatremia, which suggested malignant SIADH and facilitated an early diagnosis of small cell lung cancer (SCLC). A combined radio-chemotherapy led to a partial remission and resolution of SIADH. An early relapse was indicated by reoccurring severe hyponatremia and increased copeptin levels, which were used as surrogate markers for the antidiuretic hormone (ADH). As palliative immunochemotherapy, together with fluid restriction and solute substitution, were unable to control hyponatremia, treatment with the ADH V2-receptor antagonist tolvaptan was initiated. Over time, the dose of tolvaptan needed to be increased, paralleled by a well-documented exponential increase of copeptin levels. In summary and conclusion, this is a rare case of a secondary failure to tolvaptan with unique documentary evidence of increasing copeptin levels. This observation supports the hypothesis that exceedingly high ADH levels may lead to competitive displacement of tolvaptan from the V2 receptor.
摘要：
在肺癌患者中，抗利尿激素分泌不当（SIADH）综合征很常见。这里,我们报告一例持续性低钠血症,提示恶性SIADH，并有助于小细胞肺癌（SCLC）的早期诊断。联合放化疗可导致SIADH的部分缓解和消退。严重低钠血症和和肽素水平升高的复发表明早期复发。用作抗利尿激素（ADH）的替代标记。作为姑息性免疫化疗，连同流体限制和溶质替代，无法控制低钠血症,开始使用ADHV2受体拮抗剂托伐普坦治疗.随着时间的推移,托伐普坦的剂量需要增加，与文献记载的和肽素水平呈指数级增加平行。在总结和结论中，这是一个罕见的二次失败的情况下，托伐普坦有独特的书面证据，增加和肽素水平。该观察结果支持以下假设：极高的ADH水平可能导致托伐普坦从V2受体的竞争性置换。
