Successful treatment by tolvaptan of the syndrome of inappropriate antidiuretic hormone secretion that may be associated with chemotherapy-induced tumour lysis in a patient with small-cell lung carcinoma.

Here, we report the case of a patient with small-cell lung carcinoma (SCLC) who developed the syndrome of inappropriate antidiuretic hormone secretion (SIADH). This syndrome may be associated with chemotherapy-induced tumour lysis. Our patient was successfully treated with tolvaptan. A 70-year-old man was diagnosed with SCLC and was treated with carboplatin and etoposide. Episodes of hyponatremia occurred after every four cycles of chemotherapy that achieved tumour reduction; however, the hyponatremia was improved by temporary administration of tolvaptan. In SIADH associated with chemotherapy-induced tumour lysis, tolvaptan may improve hyponatremia and enable the continued administration of effective chemotherapy.