The growth hormone (GH) stimulation test measures the ability of the body to produce GH.
Blood is drawn several times. Blood samples are taken through an intravenous (IV) line instead of reinserting the needle each time. The test takes between 2 and 5 hours.
The procedure is done the following way:
DO NOT eat for 10 to 12 hours before the test. Eating food can change the test results.
Some medicines can affect the test results. Ask your provider if you should stop taking any of your medicines before the test.
If your child will have this test, explain how the test will feel. You may want to demonstrate on a doll. The more familiar your child is with what will happen and the purpose of the procedure, the less anxiety he or she will feel.
When the needle is inserted to draw blood, some people feel moderate pain. Others feel only a prick or stinging sensation. Afterward, there may be some throbbing or a slight bruise. These soon go away.
This test is most often done to find out whether a growth hormone deficiency (GH deficiency) is causing slowed growth.
Normal results include:
A normal value rules out hGH deficiency. In some laboratories, the normal level is 7 ng/mL (7 µg/L).
Normal value ranges may vary slightly among different laboratories. Some labs use different measurements or test different samples. Talk to your provider about the meaning of your specific test results.
If this test does not raise GH levels, there is a reduced amount of hGH stored in the anterior pituitary.
In children, this results in GH deficiency. In adults, it may be linked to adult GH deficiency.
Veins and arteries vary in size from one person 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:
Medicines that stimulate the pituitary during the test may cause side effects. The provider can tell you more about this.
Reviewed By: Neil K. Kaneshiro, MD, MHA, Clinical Professor of Pediatrics, University of Washington School of Medicine, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.