growth-hormone-tests
Reviewed
Also called: GH test, human growth hormone test, somatotropin test, growth hormone stimulation test, growth hormone suppression test
Growth hormone (GH) tests are blood tests that check if your body is making a normal amount of GH. GH controls growth and helps regulate metabolism. Because GH levels change throughout the day, a single blood test is not usually helpful. Instead, GH levels are checked using stimulation or suppression tests that involve multiple blood samples taken over a few hours. These tests help detect GH deficiency, gigantism (in children), or acromegaly (in adults).
Specimen: blood
Why this test may be ordered
- To detect GH deficiency in children with slowed growth, short stature, or delayed puberty.
- To detect GH excess (gigantism) in children with excessive growth or large hands and feet.
- To detect GH excess (acromegaly) in adults with thickened bones, enlarged facial features, or excessive sweating.
- To monitor treatment for a GH disorder.
- To evaluate pituitary gland function when other tests suggest a problem.
Preparation and collection
You may need to fast (not eat or drink) for several hours before the test.
A health care professional will take a blood sample from a vein in your arm. For a GH stimulation test, you or your child will be given a medicine through an IV that stimulates the pituitary gland to make GH, and more blood samples are taken over the next two hours. For a GH suppression test, you or your child will drink a glucose solution, and blood samples are taken every 30 minutes for two hours.
There is very little risk to having a blood test or getting an IV. There may be slight pain or bruising at the spot where the needle was put in, but most symptoms go away quickly. There is no risk to drinking the glucose solution.
Understanding results
Your healthcare provider will interpret your GH test results based on your symptoms, medical history, and other test results. The following patterns are possible:
- GH levels do not increase to a certain level during a GH stimulation test: This may indicate a GH deficiency. Limitation: This result alone does not confirm a diagnosis. Your provider will consider your symptoms and may order additional tests such as an IGF-1 test or IGBP-3 test. Next step: If your child is diagnosed with GH deficiency, they may benefit from treatment with GH supplementation (injected medicine). Early treatment can help some children grow several inches in the first year.
- GH levels do not decrease to a certain level during a GH suppression test: This may indicate a GH excess. For a child, this could mean gigantism. For an adult, it may mean acromegaly. Limitation: This result alone does not confirm a diagnosis. Your provider will consider your symptoms and may order additional tests such as an IGF-1 test or IGBP-3 test. Next step: Gigantism and acromegaly are most often caused by a pituitary tumor. Treatment may include radiation therapy, surgery, and/or medicine. If the cause is not a tumor, more tests may be needed.
- GH levels in the blood change throughout the day depending on diet and activity, so a single blood test is not usually helpful.
- Results must be interpreted by a healthcare professional; there are no universal reference intervals provided in this source.
- False positives or negatives are possible; your provider will correlate results with your symptoms and other tests.
What to do next
Your provider may order other blood tests such as an IGF-1 test or IGBP-3 test to help diagnose a GH disorder. Discuss your results and any follow-up testing or treatment options with your healthcare provider.
- What do my GH test results mean in my specific situation?
- Do I need any additional tests, such as an IGF-1 test or IGBP-3 test?
- What are the next steps based on my results?