Endocrine Abstracts

Introduction: Tolvaptan is an oral vasopressin V₂ receptor antagonist which offers a novel treatment for euvolaemic and hypervolaemic hyponatraemia. Here, we report our experience with Tolvaptan in elderly patients.

Case 1: Seventy sex-year-old lady with background of hypothyroidism, hypertension and alcohol excess presented with acute onset of confusion. Her admission Sodium [Na⁺] level was 117 mmol/l and represented an acute drop from normal level after a thiazide diuretic was introduced two days earlier. Acute thyroid dysfunction and adrenal insufficiency were excluded. Despite stopping bendroflumethiazide, [Na⁺] fell further to 108 mmol/l 48 h later. Urinary spot [Na⁺] was 29 mmol/l and urine osmolality 766 mOsm/kg in the context of euvolaemia. Following administration of 15 mg of Tolvaptan, [Na⁺] level rose to 117 mmol/l on day one and 122 mmol/l on day 2. Tolvaptan was discontinued and hyponatraemia improved on fluid restriction only with [Na⁺] level 132 mml/l 48 h later.

Case 2: Ninety one-year-old lady with known congestive cardiac failure and hypertension was admitted with a fall. She was known to have mild hyponatraemia, secondary to loop diuretic use. [Na⁺] level fell rapidly from 130 to 115 mmol/l a week post admission and continued to decline despite withholding the diuretic and ACEi, fluid restriction and Demeclocycline use (300 mg 6 hourly). Plasma osmolality was low at 245 mOsm/kg with urine osmolality at 598 mOsm/kg. Thyroid dysfunction and hypocortisolaemia were excluded. Tolvaptan 15 mg was introduced at [Na⁺] level of 106 mmol/l and resulted in gradual improvement in hyponatraemia with [Na⁺] level at 111 mmol/l on day 1, 118 mmol/l on day 2 and 127 mmo/l on day 3 post Tolvaptan. The medication was discontinued and [Na⁺] level remained stable on fluid restriction.

Conclusion: Tolvaptan is a safe and effective treatment of hyponatraemia in elderly population providing more prompt rise in serum sodium than fluid restriction and Demeclocycline.