Blood test
Growth Hormone Test
A growth hormone test checks levels of growth hormone or the related marker IGF-1, used to investigate conditions where the body makes too much or too little.
Quick answer
Growth Hormone Test: what it is and what the results mean
Growth hormone (GH) is made by the pituitary gland and controls growth and metabolism. Because its level varies through the day, it is often assessed using the steadier marker IGF-1, or with stimulation and suppression tests.
- Why it is done: It is used to investigate suspected growth hormone excess (acromegaly or gigantism) or deficiency, to explore abnormal growth in children, and to assess pituitary gland function.
- Understanding results: Results are interpreted by an endocrinologist.
What it is
Growth hormone (GH) is made by the pituitary gland and controls growth and metabolism. Because its level varies through the day, it is often assessed using the steadier marker IGF-1, or with stimulation and suppression tests.
Why it is done
It is used to investigate suspected growth hormone excess (acromegaly or gigantism) or deficiency, to explore abnormal growth in children, and to assess pituitary gland function.
What to expect
A simple blood test may measure IGF-1, but dynamic tests are often needed: a suppression test (measuring GH after a glucose drink) or a stimulation test, which take a few hours with several blood samples.
Understanding the results
Results are interpreted by an endocrinologist. High levels that fail to suppress suggest excess growth hormone, while low levels on stimulation suggest deficiency. IGF-1 gives a general picture of average GH activity.
Good to know
Risks and limitations
The blood tests are safe, though dynamic tests take time and involve several samples. Because GH levels fluctuate, a single random measurement is rarely enough, so specialist testing is usually required.
Education and reference only. This explains the test in general terms and is not medical advice. Always follow the specific instructions from the team arranging your test, and discuss your results with your clinician.
Answers
Growth Hormone Test: frequently asked questions
Why can’t a single blood test measure growth hormone?
Growth hormone is released in bursts and varies widely through the day, so one random level is unreliable. Doctors use IGF-1 or timed stimulation and suppression tests to assess it accurately.
What is IGF-1?
IGF-1 is a hormone produced in response to growth hormone. Its level is much steadier through the day, so it gives a useful overall reflection of growth hormone activity.
Related tests
Other blood test investigations
Sources
Where this is drawn from
- NHS — Tests and treatments
- NICE — diagnostic guidance
- Association for Laboratory Medicine / relevant professional body
Building patient-education content for tests or procedures?
We create clear, accurate, referenced medical explainers and decision aids for teams.