Deficiency of antidiuretic hormone (ADH), also called vasopressin, results in diabetes insipidus. As a consequence, the control of the water secretion in urine, and thus of the water volume in the body, is lost. Symptoms such as polyuria, dehydration and excessive drinking occur.
Diabetes insipidus can have its origin in the supraoptic nucleus, pituitary or kidney:
- Dysfunction or destruction of the supraoptic nucleus
- Posterior pituitary dysfunction, such as caused by a tumor, inflammation or trauma
- Impaired response by the kidney, such as a defective vasopressin receptor
The primary function of ADH is to
Extra info: As mentioned in the name, ADH is the antidiuretic hormone. So, ADH decreases the amount of water lost in urine.
I. The rise in serum osmolality stimulates thirst.
II. Reduced fluid losses in urine due to the retention of sodium ions is a result of vasopressin action.
Extra info: When the osmolality of the blood is elevated, this is monitored by specific cells in the thirstcenter in the brain. These neurons then initiate thirst. ADH or vasopressin does not act via retention of sodium ions. ADH opens water channels in order to withdraw water from the glomerular filtrate passing through the renal tubules.