Endocrine Abstracts

Introduction: Tolvaptan, a selective vasopressin 2 receptor antagonist is proving beneficial in managing hyponatremia secondary to SIADH.

Case report: A 75-year-old male with history of traumatic SAH developed hyponatremia secondary to SIADH. He had multiple admissions with symptomatic hyponatremia. His sodium level kept dropping despite putting on fluid restriction and trial of sodium chloride tablets. He was started on Tolvaptan 7.5 once weekly initially. His sodium level improved but started becoming symptomatic a day before next dose. His Tolvaptan dose was increased to one and a half of tablet each week. He became symptomatic after cutting his dose to one tablet. He was then again commenced back to previous one and half tablets per week. He is successfully maintaining his sodium level didn’t have further hospital admissions due to hyponatremia for a long time.

Investigations: Patients’ sodium level during first hospital admission was 120 mmol/l. Serum osmolality 242 mOsmol/kg, urine osmolality 656 mOsmol/kg and urinary sodium 76 mmol/l. After starting on Tolvaptan his sodium level maintained between 133-141 mmol/l. He has undergone serial serum and urine osmolality measurements.

Progress: Tolvaptan improved serum sodium and decreased hyponatremia symptoms for this patient and subsequently prevented recurrent hospital admission.

Discussion and Learning Points: 1. This was the first case in KGH where Tolvaptan was used for a longer term with regular monitoring and prescribing arrangement remained in secondary care. 2. We have calculated roughly that his Tolvaptan is costing 2950 pounds a year ( One and half tablets/ week), but his each hospital admission costs even more with 4-5 days of average stay. 3. Although Tolvaptan use in daily clinical practice is still limited due to the potential risk of overcorrections and its cost, but it can be an effective treatment option in carefully selected and monitored patient population.