Síndrome de secreción inadecuada de hormona antidiurética

Syndrome of inappropriate antidiuretic hormone secretion (SIADH) is defined as a disorder in renal free water excretion control due to the inability to suppress the secretion of antidiuretic hormone (ADH) or vasopressin. The most frequent causes are usually acquired, notable among which are central nervous system involvement, malignancy, pulmonary diseases, or drugs. Up to 35% of admitted patients have hyponatremia, of which up to 40% can be attributed to SIADH. It is considered acute when it occurs in less than 48 hours. It can trigger vomiting, convulsions, coma, and death due to cerebral herniation resulting from increased intracranial pressure. Chronic forms are more common and entail symptoms such as nausea, confusion, weakness, or agitation. In order to diagnose it, it is necessary to identify the presence of a true hypoosmolar euvolemic hyponatremia, ruling out other hormonal abnormalities or drug use. Treatment of the acute form is based on the emergency use of hypertonic saline solution, avoiding excessively rapid sodium correction that would trigger an osmotic demyelination syndrome. In the case of chronic hyponatremia, water restriction, increased osmole intake, and tolvaptan can be used in addition to acting on the triggering causes.