Alternative names 
ADH; Antidiuretic hormone; AVP; Vasopressin

Definition
ADH is a test that measures the amount of ADH in serum. ADH is a hormone found in the body. It may also be given as a medication.

How the test is performed
Adult or child:

Blood is drawn from a vein, usually from the inside of the elbow or the back of the hand. The puncture site is cleaned with antiseptic. An elastic band is placed around the upper arm to apply pressure and cause the vein to swell with blood.

A needle is inserted into the vein, and the blood is collected in an air-tight vial or a syringe. During the procedure, the band is removed to restore circulation. Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding.

In infants or young children:
The area is cleansed with antiseptic and punctured with a sharp needle or a lancet. The blood may be collected in a pipette (small glass tube), on a slide, onto a test strip, or into a small container. A bandage may be applied to the puncture site if there is any bleeding.

How to prepare for the test
Consult your health care provider about your medications before the test. Many medications, including nicotine, insulin, diuretics, lithium, morphine, alcohol, steroids, haloperidol, and clonidine can affect ADH measurements.

Infants and children:
The preparation you can provide for this test depends on your child’s age, previous experiences, and level of trust. For general information regarding how you can prepare your child, see the following topics:

 
• infant test or procedure preparation (birth to 1 year)  
• Toddler test or procedure preparation (1 to 3 years)  
• Preschooler test or procedure preparation (3 to 6 years)  
• School age test or procedure preparation (6 to 12 years)  
• Adolescent test or procedure preparation (12 to 18 years)

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 a disorder that affects the ADH level is suspected.

ADH is a hormone stored in the posterior pituitary gland in the brain. It is the primary regulator of body water. ADH acts on the kidneys to increase total body water. This decreases the plasma concentration, increasing blood volume and increasing blood pressure.

The release of ADH is controlled by cells, called osmoreceptors and baroreceptors. Osmoreceptors are specialized areas in the hypothalamus (an area in the brain). These cells sense the concentration of particles in the blood. When the concentration is high, the pituitary releases more ADH. This stimulates retention of water to dilute the body fluids. When the concentration is low, the pituitary releases less ADH. Baroreceptors are specialized areas in the heart that sense blood volume and blood pressure. The heart signals the pituitary to release more ADH when blood volume or blood pressure are low and less when they are high.

In certain diseases, the normal release of ADH is altered, and the serum level of ADH must be tested to determine the cause.

Normal Values
Values of 0 to 4.7 pg/mL are normal. Normal value ranges may vary slightly among different laboratories.

Note: pg/ml = picograms per milliliter

What abnormal results mean
Greater-than normal-levels may indicate:

 
• Acute porphyria (very rare)  
• Central nervous system infection  
• Central nervous system tumor  
• Post-surgery fluid imbalance  
• SIADH (syndrome of inappropriate ADH)  
• Pulmonary infections  
• Pulmonary or mediastinal tumors

Low values may indicate:

 
• Damage to the pituitary gland  
• Diabetes insipidus - central or nephrogenic  
• Primary polydipsia

What the risks are

 
• Excessive bleeding  
• Fainting or feeling lightheaded  
• Hematoma (blood accumulating under the skin)  
• Infection (a slight risk any time the skin is broken)  
• Multiple punctures to locate veins

Special considerations

There are none.

Medical Encyclopedia

All ArmMed Media material is provided for information only and is neither advice nor a substitute for proper medical care. Consult a qualified healthcare professional who understands your particular history for individual concerns.