Growth Hormone Releasing Hormone-Arginine Stimulation (GHRH-Arginine) Testing Fact Sheet
Overview of the Test
The GHRH-arginine stimulation test or GHRH+Arg test is a test to confirm deficiency in growth hormone. Both the hormone GHRH and the amino acid arginine can stimulate the pituitary gland into releasing growth hormone (GH). During a GHRH+Arg test, the levels of growth hormone released by the pituitary gland can be measured in the blood at regular intervals.
The GHRH+Arg test now appears to be more reliable than the commonly used insulin tolerance test (ITT) for diagnosing adult growth hormone deficiency (AGHD).
Evidence and Science behind the Test
A lack of growth hormone in children leads to short stature and other growth problems. In adults, it affects body composition and can decrease quality of life.
Growth hormone releasing hormone (GHRH) is found in the hypothalamus of the brain and its secretion increases when the body is exposed to stress (both physical and emotional). GHRH stimulates the release of growth hormone.
Somatostatin prevents GHRH and GH secretion and arginine inhibits somatostatin release, allowing growth hormone levels to increase. One 2006 study showed that subjects who received a 30 g administration of arginine before exercising were able to demonstrate a larger release of growth hormone, when compared to those subjects who just exercised.
Diagnosing growth hormone deficiency in adults requires growth hormone secretion to be stimulated in the body. Although the insulin tolerance test (ITT) is one way to stimulate a growth hormone response, the GHRH+Arg test is becoming popular. Not only does it have similar results to the ITT test, results can be reproduced and patients tolerate the testing better.
A recent validation study showed that the GHRH+Arg test and ITT had similar results although the ITT was more sensitive. Subjects who underwent the GHRH+Arg test reported fewer adverse events during the testing.
Obesity in both men and women is linked with decreased levels of growth hormone release. One study confirmed a significant inverse relationship between growth hormone response and body mass index (BMI).
How is it done?
It is important not to exercise before the test and fasting is usually required. If undergoing hormone treatments, these may need stopping before the test. In a typical test, an IV catheter is inserted into the arm and left for a while, allowing the patient to relax. A blood sample is then taken for baseline measurements. The doctor or nurse wi(2006). Oral arginine attenuates the growth hormone response to resistance exercise. Journal of Applied Physiology. Vol. 101 no. 3 848-852
- Hideo Makimura, Takara Stanley, David Mun, Sung Min You, and Steven Grinspoon. (2008). The Effects of Central Adiposity on Growth Hormone (GH) Response to GH-Releasing Hormone-Arginine Stimulation Testing in Men. J Clin Endocrinol Metab. November; 93(11): 4254–4260.
- GHRH-Arginine Stimulation Test: http://www.imperialendo.com/for-doctors/dynamic-function-testing/ghrh-arg-test
- Chanson P, Cailleux-Bounacer A, Kuhn JM, Weryha G, Chabre O, Borson-Chazot F, Dubois S, Vincent-Dejean C, Brue T, Fedou C, Bresson JL, Demolis P, Souberbielle JC. (2010). Comparative validation of the growth hormone-releasing hormone and arginine test for the diagnosis of adult growth hormone deficiency using a growth hormone assay conforming to recent international recommendations. J Clin Endocrinol Metab. Aug;95(8):3684-92
- Growth hormone stimulation test: http://www.nlm.nih.gov/medlineplus/ency/article/003377.htm
- Nigel Glynn and Amar Agha. (2012). Review Article: Diagnosill then inject GHRH and administer arginine through the IV. Blood samples are taken at regular time intervals for around two hours after the arginine infusion.
Who Does It?
Doctors, nurses and other qualified professionals.
When and How Often?
An arginine test will usually only take place when there are clinical signs of growth hormone deficiency or other pituitary gland disorders.
Cost
As it takes less time to complete than an ITT, the cost of a GHRH+Arg test may be considerably lower.
Issues
Patients may experience some mild side effects such as facial flushing, nausea and a peculiar taste sensation in the mouth. When test results are being analyzed in adults, clinicians should always consider BMI, as it has been shown that it is more difficult to stimulate growth hormone production in those who are obese.
References
- S. R. Collier, E. Collins, and J. A. Kanaley ng Growth Hormone Deficiency in Adults. Int Journal Endocrinol. Volume 20120, Article ID 972617.
Last reviewed 26/Feb/2014
