define antidiuretic hormone
Antidiuretic hormone (ADH): A relatively small (peptide) molecule that is released by the pituitary gland at the base of the brain after being made nearby (in the hypothalamus).ADH has an antidiuretic action that prevents the production of dilute urine (and so is antidiuretic). syndrome of inappropriate secretion of ADH results in the inability to put out dilute urine, perturbs fluid (and electrolyte) balance, and causes nausea, vomiting, muscle cramps, confusion and convulsions.