Antidiuretic hormone blood testDefinition:
Antidiuretic blood test measures the level of antidiuretic hormone (ADH) in blood.
Arginine vasopressin; Antidiuretic hormone; AVP; Vasopressin
How the Test is Performed:
A blood sample is needed.
How to Prepare for the Test:
Talk to your doctor about your medicines before the test. Many drugs can affect ADH level, including:
- Diuretics (water pills)
- Blood pressure medicines
- Mental condition medicines
How the Test will Feel:
When the needle is inserted to draw blood, some people feel moderate pain. Others feel only a prick or stinging. Afterward, there may be some throbbing or slight bruising. This soon goes away.
Why the Test is Performed:
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 acts on the kidneys to control the amount of water excreted in the urine.
ADH blood test is ordered when your health care provider suspects you have a disorder that affects your ADH level such as:
- Buildup of fluids in your body that are causing swelling or puffiness (edema )
- Excessive amounts of urine
- Low sodium (salt) level 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 to 5 picograms per milliliter (pcg/mL).
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:
A 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:
A lower-than-normal level may indicate:
- Damage to the hypothalamus or pituitary gland
Diabetes insipidus -- a condition in which the kidneys are not able to conserve water
- Excessive thirst (polydipsia )
- Too much fluid in the body (volume overload)
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)
Guber HA, Farag AF. Evaluation of endocrine function. In: McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods. 22nd ed. Philadelphia, Pa: Elsevier Saunders; 2011:chap 24.
Robinson AG, Verbalis JG. Posterior pituitary. In: Melmed S, Polonsky KS, Larsen PR, Kronenberg HM, eds. Williams Textbook of Endocrinology. 12th ed. Philadelphia, Pa: Elsevier Saunders; 2011:chap 10.