Tolvaptan Treatment in Syndrome of Inappropriate ADH Secretion due to Small Cell Lung Cancer

Experience of ADH receptor antagonist (-vaptanes) treatment in hyponatremia in malign patient is very limited. 68 years old male patient admitted to our department with a complain of nause, vomitting and epigastric pain. He has advanced stage of small cell lung cancer. He had treated with cisplatin and etoposide regimen 10 days ago as a first cure. We diagnosed inapropriate secretion of antidiuretic hormone syndrome (SIADH) with low sodium level (118 meq/dl). Although the treatment with water restriction and 3% NaCl infusion, sodium level was not in normal. So we ordered 30 mg tolvaptan tablet. And then sodium levels were reached normal. After one month of discharge from hospital, he has hospitilized with same symptom and diagnosis. And again we ordered same treatment procedure and tolvaptane treatment. He had normal sodium (136 mEq/dl) level during his follow up. This case demostrate that tolvaptane treatment is suitable aproaches in hyponatremia due to SIADH in oncologic patient