[Under the sword of Damocles - Resolving a complex case of hyponatremia with oral urea in clinical practice].

Introduction: hyponatraemia is the most common fluid and electrolyte disorder in clinical practice, occurring in 15-30 % of hospitalised patients, and is associated with increased morbidity, mortality and healthcare costs. Syndrome of inappropriate antidiuretic hormone secretion (SIADH) is its most common cause in the hospital setting. Case report: we present the case of a 62-year-old woman admitted for impaired consciousness secondary to severe symptomatic hypoosmolar hyponatraemia (Na+ 105.3 mmol/l). During her hospital stay, she suffered multiple complications related to her clinical condition and pre-existing comorbidities. Subsequently, following stabilisation, persistent SIADH was observed, and treatment with oral urea was initiated. The patient's prognosis was favourable, with progressive normalisation and maintenance of serum sodium concentration. Discussion: this case highlights the importance of aetiological diagnosis and the role of oral urea as an effective and safe treatment, as well as its usefulness in preventing further recurrences in patients with SIADH.