The growth hormone test measures the amount of growth hormone in the blood.
How the Test is Performed
A blood sample is needed.
How to Prepare for the Test
Your doctor may give you special instructions about what you can or cannot eat before the test.
How the Test will Feel
When the needle is inserted to draw blood, some people feel moderate pain. Others feel only a prick or stinging. Afterward, there may be some throbbing or a slight bruise. This soon goes away.
Why the Test is Performed
Growth hormone is released from the pituitary gland. This is a small organ in the brain, located behind the nose.
- Too much growth hormone can cause abnormally increased growth patterns called acromegaly in adults and gigantism in children.
- Too little growth hormone can cause a slow or flat rate of growth in children, and changes in energy, muscle mass, cholesterol levels, and bone strength in adults.
The growth hormone test may be used to monitor response to acromegaly treatment.
The normal range for growth hormone level is typically:
- 1 through 9 nanograms per milliliter (ng/mL) for males
- 1 through 16 ng/mL for females
GH is released in pulses. This is why random GH measurements are rarely useful. A higher level may be normal if the blood was drawn during a pulse. A lower level may be normal if the blood was drawn around the end of a pulse. GH is most useful when measured as part of a stimulation or suppression test.
Normal value ranges may vary slightly among different laboratories. Some labs use different measurements or test different specimens. Talk to your doctor about the meaning of your specific test results.
Veins and arteries vary in size from one patient to another, and from one side of the body to the other. Obtaining a blood sample from some people may be more difficult than from others.
Other risks associated with having blood drawn are slight, but may include:
- Excessive bleeding
- Fainting or feeling light-headed
- Hematoma (blood accumulating under the skin)
- Infection (a slight risk any time the skin is broken)
Guber HA, Farag AF. Evaluation of endocrine function. In: McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods. 22nd ed. Philadelphia, PA: Elsevier Saunders; 2011:chap 24.
Hosono H, Cohen P. Hyperpituitarism, tall stature, and overgrowth syndromes. In: Klliegman RM, Stanton BF, St. Geme JW III, et al., eds. Nelson Textbook of Pediatrics. 19th ed. Philadelphia, PA: Elsevier Saunders; 2011:chap 554.
Update Date 5/10/2014
Updated by: Brent Wisse, MD, Associate Professor of Medicine, Division of Metabolism, Endocrinology & Nutrition, University of Washington School of Medicine, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial Team.