Three interesting cases of syndrome of inappropriate antidiuretic hormone secretion

The syndrome of inappropriate antidiuretic hormone secretion (SIADH) is an etiologically-diverse pathological condition resulting from the elevation in both ectopic and autonomic secretion of the antidiuretic hormone (ADH) by neoplastic tissue; excessive stimulation of the hypothalamic-pituitary axis, e.g. in pulmonary diseases, central nervous system (CNS) abnormalities, endocrine glands dysfunction or due to the use of some medications; intensification of renal ADH action by certain medications and action of substances chemically-related to vasopressin. The clinical characteristics of the syndrome are comprised of the presence of inadequately concentrated urine, hyponatremia, and hypo-osmolal blood serum, as well as weight gain. To show the variety of its causes and courses the article presents three cases of patients diagnosed with SIADH in the Department of Internal Medicine. In each of them the syndrome of inappropriate antidiuretic hormone secretion manifested in clinical laboratory tests in the form of hyponatremia