Antidiuretic hormone, also known as ADH or vasopressin, is a hormone secreted by the pituitary gland. Its primarily role is to stimulate the kidneys to reabsorb water, rather than passing it, and it is designed to act as part of the complex system which regulates blood pressure and the balance of salts in the body. People with levels of this hormone which are too high or too low can experience medical problems such as diabetes insipidus.
Several circumstances can trigger production of antidiuretic hormone by the pituitary gland. Falls in blood pressure, changes in plasma volume, and secretions from the gall bladder can all play a role in the secretion of this hormone. The hormone travels to the kidneys, where it directs the structures in the kidneys to reabsorb the water which flows through the kidneys, and it also ends up in the brain, where it interfaces with vasopressin receptors. In the brain, vasopressin appears to play a role in the formation of memories, and it has been linked with certain social behaviors.
When levels of antidiuretic hormone rise, the blood pressure rises as well. If levels of this hormone get too high, people develop fluid overload, and the levels of salts in their body go out of balance, becoming heavily diluted because the body is retaining too much water. This can develop into hyponatremia, a very serious medical condition which can cause complications with the brain and lungs. If there is not enough antidiuretic hormone being produced by the pituitary gland, people can develop diabetes insipidus, characterized by excessive thirst and frequent urination.
Hospitalized patients sometimes develop syndrome of inappropriate antidiuretic hormone (SIADH). Patients with this condition secrete too much antidiuretic hormone, stressing the body and leading to fluid and electrolyte imbalances. Because SIADH is known to be a problem in hospitalized patients, regular screening may be performed as a routine part of patient care to ensure that it is identified and addressed early.
If patients develop a deficiency or excess of this hormone, a doctor will need to interview the patient and perform screening to determine the cause of the problem so that it can be addressed. Treatments may be able to restore the body to normal function, or a patient's condition could be managed with the appropriate care. Failure to identify over or underproduction of antidiuretic hormone can have complications for the patient, and it may lead to permanent damage.