OTHR-36. Management of Central Diabetes Insipidus (CDI) with Low-Dose Vasopressin Infusion in Patients with Non-Germinomatous Germ Cell Tumors (NGGCT) Requiring Hyperhydration during Chemotherapy

Primary intracranial germ cell tumors (GCT) represent 3-5% of central nervous system tumors with non-germinomatous germ cell tumors (NGGCTs) comprising approximately one-third. Located in the pineal and suprasellar regions, the tumors can cause central diabetes insipidus (CDI). Induction chemotherapy for NGGCT includes ifosfamide. Due to the risk of hemorrhagic cystitis associated with ifosfamide, 3000 mL/m2/day of intravenous fluids is administered. Oral desmopressin (DDAVP), the mainstay of treatment for CDI, has a long duration of action, variable intensity and can lead to hyponatremia and water intoxication due to the retention of large quantities of free water. Therefore, DDAVP is held during hyperhydration resulting in significant diuresis leading to patient discomfort and increased risk for wide electrolyte fluctuations. The volume of dextrose-containing IV fluids also places patients at risk for hyperglycemia and other metabolic disturbances. Patients with NGGCTs and CDI at our institution are admitted to the ICU for ifosfamide cycles due to the need for close monitoring and prompt interventions. ICU admission can delay therapy and potentially places patients in a setting where staff are unfamiliar with chemotherapy administration, increasing the risk of safety-related events. From a cost, resource, and patient care perspective, these admissions are suboptimal. This prompted a search for evidence to maintain patients safely out of the ICU. A literature search provided case studies citing the use of low-dose IV vasopressin. In collaboration with our endocrine and pharmacy colleagues we created a protocol to treat patients with CDI receiving chemotherapy with hyperhydration with a low-dose, easily titratable intravenous vasopressin infusion, to keep urine mildly diluted to allow enough diuresis to decrease injury while preventing excessive fluid losses and wide variations in electrolytes.