[Severe idiopathic hyponatremia caused by ADH inappropriate secretion in the elderly].

We report on seven elderly patients with severe hyponatremia (plasma sodium < 125 meq/l). All were symptomatic for central nervous system disturbances, weakness, nausea/vomiting and met clinical and laboratory criteria for the diagnosis of inappropriate secretion of antidiuretic hormone (SIADH). Investigations performed to determine the etiology of the syndrome gave negative results, so that the form was considered to be idiopathic.