Growth Hormone Antibody

Does this test have other names?

Anti-human GH antibodies, growth hormone neutralizing antibodies

What is this test?

This test looks for growth hormone (GH) antibodies in your blood.

GH is used to manage height issues linked to a growth hormone deficiency (GHD). If your body makes GH antibodies in response to GH treatment, the treatment may not work the way it should.

Why do I need this test?

You may need this test if your healthcare provider suspects that your GH treatment isn't working anymore. The most common symptom of GH antibodies is a lack of growth even with adequate doses of GH.

Children with GHD often fail to grow on a normal schedule. Signs may include decreased height with a normal weight and immature facial structure, notably a large forehead and an underdeveloped nasal bridge. A child's voice may not mature, his or her hair may not grow well, and the transition to adolescence is often delayed.

Ten to 20% of people who get GH therapy will develop GH antibodies in reaction to it. This often happens soon after GH treatment starts—usually after a 3- to 6-month growth period. The antibodies can cause the treatment to not work.

The good news is that GH antibodies are becoming increasingly rare thanks to the use of a synthetic, or man-made, growth hormone.

What other tests might I have along with this test?

Your healthcare provider may also order a blood test for insulin-like growth factor I (IGF-I). Low levels of IGF-I can be a sign that the GH may not be working the way it should.

What do my test results mean?

Test results may vary depending on your age, gender, health history, the method used for the test, and other things. Your test results may not mean you have a problem. Ask your healthcare provider what your test results mean for you. 

Normal results are negative, meaning that no GH antibodies were found. Positive results mean that GH antibodies were found and that your GH therapy may no longer be working.

How is this test done?

The test is done with a blood sample. A needle is used to draw blood from a vein in your arm or hand. 

Does this test pose any risks?

Having a blood test with a needle carries some risks. These include bleeding, infection, bruising, and feeling lightheaded. When the needle pricks your arm or hand, you may feel a slight sting or pain. Afterward, the site may be sore. 

What might affect my test results?

Other factors aren't likely to affect your results.

How do I get ready for this test?

You don't need to prepare for this test. Be sure your healthcare provider knows about all medicines, herbs, vitamins, and supplements you are taking. This includes medicines that don't need a prescription and any illicit drugs you may use.