Antidiuretic hormone (ADH), or arginine vasopressin (AVP), is a peptide hormone produced by the hypothalamus, and stored in the posterior pituitary gland until the hypothalamus signals its release in response to a change in serum osmolarity or blood volume. ADH acts on the kidneys at the renal collecting duct, concentrating the urine by promoting the reabsorption of water and salt.\n