title: Hyponatremia and pituitary adenoma: think twice about the etiopathogenesis.
abstract: Pituitary adenomas may be the cause of the syndrome of inappropriate secretion of antidiuretic hormone (SIADH), although few cases have so far been reported. We described a case of hypotonic hyponatremia in a 76-yr-old man with a pituitary macroadenoma. He had a recent history of two syncopal attacks which had occurred in the last two months. Baseline assessment demonstrated a sodium serum level of 114 mEq/l. Clinically, the patient appeared euvolemic. Thyroid and adrenal function testing did not show any abnormality. Plasma and urinary osmolality (238 and 186 mOsm/kg, respectively) were in agreement with the diagnosis of SIADH. Accordingly, 3% hypertonic saline solution was started, followed by water intake restriction when natremia reached 126 mEq/l. A computed tomography (CT) scan of the chest revealed the presence of a 2-cm lesion in the azygos-esophageal recess. Because the nature of the lesion appeared uncertain, antibiotic therapy was initiated. After one month, a new CT scan did not show any evidence of the mediastinic mass. Sodium serum level was within the normal range (141 mEq/l) and remained stable thereafter, without fluid restriction. This case very well demonstrates that, in the presence of hyponatremia due to SIADH, more frequently associated co-morbidities (ie mediastinic diseases) have to be searched, even in the presence of a possible, yet rare, cause of this syndrome (ie pituitary adenoma).
authors.affiliation: Endocrine Unit, Department of Clinical Physiopathology, University of Florence, 50139 Florence, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Zogheri
authors.forename: A
authors.initials: A
authors.lastname: Di Mambro
authors.forename: M
authors.initials: M
authors.lastname: Mannelli
authors.forename: M
authors.initials: M
authors.lastname: Serio
authors.forename: G
authors.initials: G
authors.lastname: Forti
authors.forename: A
authors.initials: A
authors.lastname: Peri
mesh_terms: D000368:Aged; D003937:Diagnosis, Differential; D006801:Humans; D007010:Hyponatremia / Q000000981:diagnostic imaging* / Q000209:etiology* / Q000503:physiopathology; D008297:Male; D010911:Pituitary Neoplasms / Q000000981:diagnostic imaging* / Q000209:etiology* / Q000503:physiopathology; D011859:Radiography; D013577:Syndrome