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.
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).
Nancy J. Rennert, MD, Chief of Endocrinology & Diabetes, Norwalk Hospital, Associate Clinical Professor of Medicine, Yale University School of Medicine, New Haven, CT. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.