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Vol.58 No.2 contents | Japanese/English |
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- Case Report -
Effectiveness of Tolvaptan in a Case of Refractory Syndrome of Inappropriate Secretion of Antidiuretic Hormone Caused by Small Cell Lung Cancer
Erika Kobayashi1, Yu Nakanishi2, Yasushi Horimasu2, Hiroshi Iwamoto2, Kazunori Fujitaka2, Noboru Hattori21Postgraduate Clinical Training Center, 2Department of Respiratory Internal Medicine, Hiroshima University Hospital, Japan
Background. Syndrome of inappropriate secretion of antidiuretic hormone (SIADH), one of the major complications of small cell lung cancer (SCLC), is characterized by various symptoms associated with hyponatremia caused by the inappropriate secretion of ADH or by the enhanced sensitivity of the kidney to vasopressin receptor 2. We herein report a case of refractory SIADH that was related to SCLC, in a patient in whom hyponatremia relapsed even after a temporary improvement was achieved by mozavaptan treatment, despite prolonged tumor shrinkage following effective chemotherapy. The patient was finally successfully treated with tolvaptan. Case. A 73-year-old man was diagnosed with extensive SCLC (cT4N2M1b, Stage IV) accompanied by SIADH in May 201X. The patient showed a partial response to chemotherapy with carboplatin plus etoposide; nonetheless, his hyponatremia persisted. In addition to water restriction, oral Na supplementation and the administration of furosemide, mozavaptan was effective for elevating his serum Na concentration. However, after the course with mozavaptan treatment, his serum Na concentration dropped again to approximately 120 mEq/l. During the fifth cycle of chemotherapy, he was hospitalized due to nausea, anorexia, headache, and exacerbated hyponatremia (Na 113 mEq/l). Treatment with tolvaptan had been initiated, and both his symptoms and hyponatremia improved. At the present time, he has taken tolvaptan continuously, without any severe adverse events, for over 7 months and his serum Na concentration has remained within a reasonable range. Conclusion. Tolvaptan can be an effective therapeutic option for refractory SIADH related to SCLC.
key words: Syndrome of inappropriate secretion of antidiuretic hormone, Small cell lung cancer, Mozavaptan, Tolvaptan
Received: November 15, 2017
Accepted: January 28, 2018
JJLC 58 (2): 132-137, 2018
