ADH is a test that measures the amount of antidiuretic hormone (ADH) in blood. ADH is a hormone that is produced in a part of the brain called the hypothalamus. It is then stored and released from the pituitary gland, a small gland at the base of the brain.
ADH helps manage the amount of water in the body by acting on the kidneys.
Arginine vasopressin; Antidiuretic hormone; AVP; Vasopressin
How the test is performed
A blood sample is needed. For information on how this is done, see: Venipuncture
How to prepare for the test
Talk to your health care provider about your medications before the test. Many medications can affect ADH measurements, including:
How the test will feel
When the needle is inserted to draw blood, some people feel moderate pain, while others feel only a prick or stinging sensation. Afterward, there may be some throbbing.
Why the test is performed
This test is performed if your health care provider suspects you have a disorder that affects your ADH level. ADH helps manage the amount of water in the body by acting on the kidneys.
Your health care provider may order ADH levels if you have:
- Buildup of fluids in your body that are causing swelling or puffiness
- Excessive amounts of urine
- Low sodium ("salt") levels in your blood
- Thirst that is intense or uncontrollable
Certain diseases affect the normal release of ADH. The blood level of ADH must be tested to determine the cause of the disease. ADH may be measured as part of a "water restriction test" to find the cause of a disease.
Normal values for ADH can range from 1 - 5 pg/mL
Note: pg/mL = picograms per milliliter
The examples above are common measurements for results of these tests. Normal value ranges may vary slightly among different laboratories. Some labs use different measurements or may test different specimens. Talk to your doctor about the meaning of your specific test results.
What abnormal results mean
Higher-than-normal levels may occur when too much ADH is released, either from the brain where it is made, or from somewhere else in the body. This is called syndrome of inappropriate ADH (SIADH).
Causes of SIADH include:
Lower-than-normal levels may indicate:
- Damage to the pituitary gland
- -- a condition in which the kidneys are not able to conserve waterDiabetes insipidus
- Primary polydipsia
What the risks are
Veins and arteries vary in size from one patient to another and from one side of the body to the other. Obtaining a blood sample from some people may be more difficult than from others.
Other risks associated with having blood drawn are slight but may include:
- Excessive bleeding
- Fainting or feeling light-headed
- Hematoma (blood accumulating under the skin)
- Infection (a slight risk any time the skin is broken)
Robinson AG, Verbalis JG. Posterior pituitary. In: Kronenberg HM, Melmed S, Polonsky KS, Larsen PR, eds. . 12th ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 10.