Growth hormone test
The growth hormone test measures the amount of growth hormone in the blood.
How the test is performed
A blood sample is needed. For information on how this is done, see: Venipuncture
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, while others feel only a prick or stinging sensation. Afterward, there may be some throbbing.
Why the test is performed
Growth hormone is released from an area just below the brain called the anterior pituitary gland.
- Too much growth hormone can cause abnormal 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 muscle mass, cholesterol levels, and bone strength in adults.
The growth hormone test may be used to monitor response to acromegaly treatment.
Different tests are used to diagnose growth problems:
- GHRH or GHRH-arginine stimulation (to help diagnose a lack of growth hormone)
- Growth hormone stimulation test
- IGF-1 levels
- Oral glucose tolerance suppression (to help diagnose too much growth hormone)
The normal range for growth hormone levels is typically:
- 1 - 9 ng/mL (male)
- 1 - 16 ng/mL (female)
GH is released in pulses. 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.
Normal value ranges may vary slightly among different laboratories. Talk to your doctor about the meaning of your specific test results.
What abnormal results mean
High levels of growth hormone may indicate:
- Growth hormone resistance
- Pituitary tumor
Low levels of growth hormone may indicate:
- Growth hormone deficiency
- Hypopituitarism (low function of the pituitary gland)
What the risks are
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)
Melmed S, Kleinberg D. Pituitary masses and tumors. In: Melmed S, Polonsky KS, Larsen PR, Kronenberg HM, eds. Williams Textbook of Endocrinology. 12th ed. Philadelphia, PA: Saunders Elsevier; 2011: chap 9.
Molitch ME. Anterior pituitary. In: Goldman L, Schafer AI, eds. Cecil Medicine. 24th ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 231.
Hosono H, Cohen P. Hyperpituitarism, tall stature, and overgrowth syndromes. In: Klliegman RM, Stanton B, St. Geme J, Schor N, Behrman RE, eds. Nelson Textbook of Pediatrics. 19th ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 554.
Last reviewed 5/31/2012 by Shehzad Topiwala, MD, Chief Consultant Endocrinologist, Premier Medical Associates, The Villages, FL. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M. Health Solutions, Ebix, Inc.
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