Antidiuretic Hormone (ADH)
Arginine Vasopressin (AVP), also known as Vasopressin, Argipressin or Antidiuretic Hormone (ADH) is a peptide hormone. It is derived from a preprohormone precursor that is synthesized in the hypothalamus and stored in vesicles at the posterior pituitary. Most of it is stored in the posterior pituitary to be released into the blood stream; however, some of it is also released directly into the brain.
AVP regulates the body's retention of water; it is released when the body is dehydrated and causes the kidneys to conserve water (increasing the permeability to water of the distal convoluted tubules and collecting tubules in the nephrons), thus concentrating the urine, and reducing urine volume. It also raises blood pressure by inducing moderate vasoconstriction (increasing the resistance of the peripheral vessels). It is an important compensatory mechanism for restoring blood pressure in hypovolemic shock. In addition, it has a variety of neurological effects on the brain, having been found (memory, image, aggression, blood pressure regulation and temperature regulation).
Vasopressin is secreted from the posterior pituitary gland in response to reductions in plasma volume, in response to increases in the plasma osmolality, and in response to Cholecystokinin by the small intestine. Ethanol (alcohol) reduces secretion.
The vasopressin that is measured in peripheral blood is almost all derived from secretion from the posterior pituitary gland (except in cases of vasopressin-secreting tumours).
Role in disease
Decreased vasopressin release or decreased renal sensitivity to vasopressin leads to diabetes insipidus, a condition featuring hypernatremia, polyuria and polydipsia (thirst).
High levels of vasopressin secretion (syndrome of inappropriate antidiuretic hormone, SIADH) and resultant hyponatremia occurs in brain diseases and conditions of the lungs (Small cell lung carcinoma). In the perioperative period, the effects of surgical stress and some commonly used medications (e.g. opiates, syntocinon, anti-emetics) lead to a similar state of excess vasopressin secretion. This may cause mild hyponatremia for several days.
Now in Saridar Laboratories, ADH is available and results will be ready after 2 days.