ADH

Definition

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.

Alternative Names

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:

• Alcohol
• Clonidine
• Diuretics
• Haloperidol
• Insulin
• Lithium
• Morphine
• Nicotine
• Steroids

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 Results

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:

• Brain injury or trauma
• Brain tumors
• Fluid imbalance after surgery
• Infection in the brain or the tissue that surrounds the brain
• Infection in the lungs
• Small cell carcinoma lung cancer
• Stroke

Lower-than-normal levels may indicate:

• Damage to the pituitary gland
• Diabetes insipidus -- a condition in which the kidneys are not able to conserve water
• Primary polydipsia

Risks

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)

References

Robinson AG, Verbalis JG. Posterior pituitary. In: Kronenberg HM, Melmed S, Polonsky KS, Larsen PR, eds. Williams Textbook of Endocrinology. 12th ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 10.

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