Growth Hormone (Blood)
Does this test have other names?
What is this test?
This test measures the amount of growth hormone (GH) in your blood.
GH is made in your pituitary gland. It affects height, bone, and muscle growth in
children. It affects how adults feel and look, as well as their bone and muscle health.
GH is made in a pulse-like manner. Most GH is made while you sleep. When you're awake,
little or possibly no GH is found in your blood. That makes it hard to test your GH
level. Specialists have developed methods to figure out if you make too much or too
little by testing your blood over time after you have been given a suppressing agent,
such as glucose, or a stimulating agent, like insulin.
Why do I need this test?
You may need this test if your healthcare provider suspects you have a GH problem.
Decreased bone density
Reduced muscle strength
Increased lipid levels, or fats in your blood
Acromegaly, or excessive GH disease
Your child might need this test if he or she has these signs:
Symptoms of gigantism
You may also have this test if you have been given GH treatment, so your healthcare
provider can watch your dosage and change it if needed.
You may have this test if you are a young adult who has been taking GH for years but
may no longer need it.
You may also need this test if you have acromegaly, so your healthcare provider can
keep an eye on your disease.
What other tests might I have along with this test?
Your healthcare provider may also order a blood test for insulin-like growth factor-1
(IGF-1). GH tells your liver to make IGF-1, so usually GH and IGF-1 are correlated.
GH is secreted in pulses while you sleep, but IGF is always found in your blood. That
makes it much easier to find IGF-1 in your blood than GH.
Your healthcare provider may also order other tests to look for a possible growth
hormone deficiency. These tests include:
Tests that use other medicines like clonidine, L-dopa, or glucagon
If your healthcare provider suspects that you have excess growth hormone, he or she
may order an oral glucose tolerance test.
What do my test results mean?
Many things may affect your lab test results. These include the method each lab uses
to do the test. Even if your test results are different from the normal value, you
may not have a problem. To learn what the results mean for you, talk with your healthcare
If your levels are higher, it may mean you have:
If your levels are lower, it may mean you have:
Levels that are higher or lower may also be caused by chronic malnutrition, cirrhosis,
and stress from surgery or a serious infection.
How is this test done?
The test requires a blood sample, which is drawn through a needle from a vein in your
Does this test pose any risks?
Taking a blood sample with a needle carries risks that include bleeding, infection,
bruising, or feeling dizzy. When the needle pricks your arm, you may feel a slight
stinging sensation or pain. Afterward, the site may be slightly sore.
What might affect my test results?
Certain foods and beverages, especially those high in protein, can affect your results.
Certain medicines, including oral contraceptives containing estrogen, can also affect
your results. Great physical or emotional stress and sleeping can affect your results.
How do I get ready for this test?
Your healthcare provider may ask you to stop taking oral estrogens for a time before
this test. You also may be told to not eat or drink anything but water for a certain
amount of time before the 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.