ESPE Abstracts

Introduction: Post-operative management of fluid and electrolyte imbalance after surgery for pituitary or suprasellar tumors could be challenging. Post-operative course could include diabetes insipidus (DI) (transient or permanent) or a classical triphasic response (initial phase of DI followed by a second phase of transient SIADH and third and final phase of permanent DI). Mainstay of management of SIADH in these patients involves fluid restriction. At times, treatment with hypertonic saline and diuretics might be needed but may not be sufficient to manage severe hyponatremia. Tolvaptan is a V2 receptor antagonist that blocks the action of ADH and could be of potential benefit in SIADH management. We report a 15 year old boy who developed severe SIADH following suprasellar surgery, which was successfully treated with Tolvaptan.

Case report: A 15 year old boy with a medulloblastoma and metastasis in the sellar region underwent surgical resection of the metastatic mass. Post-surgery, he had water imbalance and a triphasic response in which initial phase of transient DI lasted for 3 days and was treated with desmopressin and additional fluids. This was followed by a phase of transient SIADH which was initially treated with fluid restriction and then with hypertonic saline and furosemide. Despite this, he had persistent hyponatremia and a single dose of Tolvaptan (15 mg) was given which showed improvement in the sodium concentration (126 mmol/l to 133 mmol/l) with a prompt recovery from SIADH (serum osmolality increased from 265 mmol/l to 303 mmol/l and the urine output increased from 0.2 ml/kg/hr to 4.4 ml/kg/hr). Overall, the SIADH phase lasted for 5 days after which he developed persistent DI which was managed with desmopressin.

Conclusion: Tolvaptan could be a potential treatment option for resistant SIADH in children and young people.