Use of conivaptan to allow aggressive hydration to prevent tumor lysis syndrome in a pediatric patient with large-cell lymphoma and SIADH.

The available treatment options for hyponatremia secondary to SIADH are limited and not completely effective. Conivaptan is a vasopressin 1a and 2 receptor antagonist recently approved by the US Food and Drug Administration (FDA) for treating euvolemic and hypervolemic hyponatremia in adult patients. However, data on efficacy and safety of conivaptan in pediatrics are limited. We report a case of a 13-year-old boy with extensively metastasized anaplastic large-cell lymphoma. He also developed hyponatremia due to syndrome of inappropriate antidiuretic hormone secretion (SIADH) prior to chemotherapy initiation. SIADH management in this case was complicated when fluid restriction was not safely attainable. Conivaptan played a significant role in this situation by allowing provision of a large amount of intravenous fluid prior to and during induction chemotherapy. It proved to be an important component in preventing uric acid nephropathy/tumor lysis syndrome. Conivaptan induced free-water clearance as indicated by increased urine output and decreased urine osmolality. The patient responded to conivaptan without any adverse effects.