Growth Hormone Stimulation Test- Why am I having this test?
Growth hormone stimulation test is used to check your levels of growth hormone and to evaluate your body’s ability to produce this hormone. The growth hormone promotes normal growth from birth through the end of puberty.
The test may be done if your health care provider thinks that you may have growth hormone levels that are too low (deficient).
What is being tested?
This test measures the amount of growth hormone in your blood to determine how much your body is producing. Growth hormone is made by the pituitary gland, which is a small organ located in the center of the brain.
Growth hormone is released in different amounts during the day, so testing it randomly may not give an accurate measurement. For this test, steps are taken that normally stimulate the body to temporarily produce more growth hormone. For example, when blood sugar (glucose) levels are low, the body normally makes more growth hormone. By causing you to experience low blood sugar (hypoglycemia), your health care provider can determine if your body has the ability to produce growth hormone as it should. One or more of the following stimulants can be used to test the growth hormone response:
- Insulin-induced hypoglycemia. This is when your blood sugar level is lowered to less than 40 mg/dL.
- Certain medicines, such as glucagon or arginine.
- Heavy exercise.
When two of these stimulants are used to perform the growth hormone stimulation test, it is called a double-stimulated test.
What kind of sample is taken?
Blood samples are required for this test. They are usually collected by inserting an IV into one of your veins. Insulin or medicines used to stimulate the production of growth hormone may also be given through the IV. Blood samples are taken at various intervals during the test.
How do I prepare for this test?
Do noteat or drink anything except water after midnight on the night before the test or as told by your health care provider.
Tell a health care provider about:
- All medicines you are taking, including vitamins, herbs, eye drops, creams, and over-the-counter medicines.
- Any medical conditions you have. It may not be safe for you to have this test if you have epilepsy, cerebrovascular disease, a history of heart attack, or low baseline cortisol levels in your blood.
How are the results reported?
Your test results will be reported as values. Your health care provider will compare your results to normal ranges that were established after testing a large group of people (reference ranges). Reference ranges may vary among labs and hospitals. For this test, common reference ranges are:
- Men: Less than 5 ng/mL or less than 5 mcg/L (SI units).
- Women: Less than 10 ng/mL or less than 10 mcg/L (SI units).
- Children:
- Newborn: 5–23 ng/mL or 5–23 mcg/L (SI units).
- 1 week old: 2–27 ng/mL or 2–27 mcg/L (SI units).
- 1–12 months old: 2–10 ng/mL or 2–10 mcg/L (SI units).
- Females older than 1 year: 0–10 ng/mL or 0–10 mcg/L (SI units).
- Males older than 1 year: 0–6 ng/mL or 0–6 mcg/L (SI units).
What do the results mean?
Abnormally high levels of growth hormone may indicate problems such as:
- Gigantism.
- Acromegaly.
- Anorexia nervosa.
- Chronic or high levels of stress.
- Major surgery.
- Hypoglycemia.
- Starvation.
Abnormally low levels of growth hormone may indicate problems such as:
- Growth hormone deficiency.
- Pituitary gland malfunction (pituitary deficiency).
- Dwarfism.
- Hyperglycemia.
- Failure to thrive.
- Delayed sexual maturity.
Talk with your health care provider about what your results mean.
Questions to ask your health care provider
Ask your health care provider, or the department that is doing the test:
- When will my results be ready?
- How will I get my results?
- What are my treatment options?
- What other tests do I need?
- What are my next steps?
Summary
- The growth hormone stimulation test is used to check your levels of growth hormone and to evaluate your body’s ability to produce this hormone.
- This hormone promotes normal growth from birth through the end of puberty.
- The test may be done if your health care provider thinks that you may have growth hormone levels that are too low (deficient).
- For this test, steps are taken that normally stimulate the body to temporarily produce more growth hormone.
- Blood samples are required for this test.
