A 61-year-old woman was admitted to our ward - after her third visit to the Emergency Department in two months - because of progressive lethargy, weakness, and persistent euvolaemic hyponatraemia. Based on the results of the first diagnostic workup (complete blood count, serum and urinary biochemistry), a diagnosis of Syndrome of Inappropriate Antidiuretic Hormone Secretion (SIADH) was established. A comprehensive second diagnostic workup was performed, leading to the diagnosis of anterior hypopituitarism due to primary empty sella syndrome, a rare multiple hormone deficit which could result in devastating consequences if left untreated.