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.
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 your test.
Your provider may order a GH stimulation or a GH suppression test, depending on whether symptoms show a possible GH deficiency or a GH excess. A GH stimulation test is used to check for a GH deficiency. Your child (or you) will be given a medicine through an intravenous (IV) line that stimulates (causes) the pituitary gland to make GH. A GH suppression test is used to check for a GH excess. You or your child will drink a solution that contains water and glucose (sugar).
There is very little risk to you or your child in 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
GH levels in your blood change throughout the day, depending on your diet and activity levels. So, a standard blood test doesn't usually provide helpful information about GH levels.
- GH doesn't increase enough during a stimulation test: If GH levels don't increase to a certain level during a GH stimulation test, it may mean that there is a GH deficiency. Limitation: Unlike GH, IGF-1 levels are more stable throughout the day. Next step: If your child is diagnosed with GH deficiency, they may benefit from treatment with GH supplementation.
- GH doesn't decrease enough during a suppression test: it may mean that there is a GH excess. For your child, this could mean they have gigantism. For you, it may mean you have acromegaly. Limitation: But if the cause is not a tumor, you or your child may need more tests to identify the cause. Next step: Gigantism and acromegaly are most often caused by a tumor in the pituitary gland. Treatment for the tumor may include radiation therapy, surgery, and/or medicine.
- 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 to help diagnose a GH disorder.
- 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?
Evidence source
Source: U.S. National Library of Medicine (MedlinePlus). Practices and reference ranges may differ in your country.