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To help diagnose growth hormone (GH) deficiency or, less commonly, growth hormone excess; to evaluate pituitary function; to monitor the effectiveness of treatment for excess GH
When a child has slow growth, short stature, and delayed motor development or sometimes when an adult has decreased bone density and/or muscle strength and elevated blood lipid levels that could be related to growth hormone deficiency; when a child or adult has signs and symptoms suggestive of growth hormone excess, which can cause two rare conditions, gigantism and acromegaly, respectively; when a pituitary disorder is suspected and other pituitary hormone levels are abnormal
Usually several blood samples, drawn at timed intervals from veins; sometimes a single sample of blood, drawn following a fast and rest, after a period of strenuous exercise, or after drinking a glucose (sugar) solution
Follow any instructions you are given, such as to fast, in order to prepare for this test.
Growth hormone (GH) is a hormone that is essential for normal growth and development in children. It promotes proper linear bone growth from birth through puberty. In both children and adults, growth hormone helps regulate the rate at which the body both produces energy from food (metabolism) and makes lipids, proteins, and glucose (sugar). It also helps regulate the production of red blood cells and muscle mass.
Growth hormone is produced by the pituitary gland, a small gland located at the base of the brain behind the bridge of the nose. It is normally released into the blood in pulses throughout the day and night with peaks that occur mostly during the night. Because of this, a single measurement of the level of GH in blood is difficult to interpret and not usually clinically useful. The value will be higher if the sample is taken during a pulse and lower if it is taken during a period between pulses.
Therefore, procedures called growth hormone stimulation and suppression tests are most often used to diagnose conditions caused by growth hormone deficiency or excess. These procedures are used in conjunction with signs and symptoms and growth factor levels (i.e., insulin-like growth factor-1 (IGF-1) and insulin-like growth factor binding protein 3). See "How is the test used?" under Common Questions for more detail.
Some children have GH deficiency at birth (congenital), but some may develop a deficiency later due, for example, to a brain injury or tumor. These conditions can affect the pituitary gland, causing a decrease in pituitary function, resulting in a lowered production of pituitary hormones (hypopituitarism). Sometimes, the cause of the deficiency is not known, a category referred to as "idiopathic."
In adults, growth hormone plays a role in regulating bone density, muscle mass, and glucose and lipid metabolism. It can also affect heart and kidney function. Deficiencies may begin in childhood or develop in adulthood. A deficiency can develop, for example, because of damage to the pituitary gland caused by a head injury, brain tumor, or surgery or radiation treatment. This can result in a decrease in pituitary hormones (hypopituitarism).
Excess GH is most often due to a pituitary tumor (usually benign) that produces GH.
Too much GH in children can cause their long bones to continue to grow beyond puberty, resulting in the extremely rare condition, gigantism, with heights of 7 feet or more. Those with excess GH may also have thickening of facial features, general weakness, delayed puberty, and headaches. Pituitary tumors releasing excess growth hormone can cause loss of vision if they grow very large.
Excess GH in adults can lead to the rare condition, acromegaly, marked not by bone lengthening but by bone thickening. Although symptoms such as skin thickening, sweating, fatigue, headaches, and joint pain can be subtle at first, increased GH levels can lead to enlarged hands and feet, enlarged facial bones, carpal tunnel syndrome, and abnormally enlarged internal organs. Excess GH can also cause skin tags and intestinal polyps.
Frequently, the pituitary tumor causing the excess can be surgically removed and/or treated with drugs or radiation. In most cases, this will cause GH and IGF-1 levels to return to normal or near normal levels.
If left untreated, both acromegaly and gigantism can lead to complications such as type 2 diabetes, increased risk of cardiovascular disease, high blood pressure, arthritis, and in general, a decreased lifespan.
How is the sample collected for testing?
Growth hormone is released in pulses, so a single measurement of the blood level is not normally clinically useful. Therefore, growth hormone levels are usually measured using growth hormone suppression or stimulation procedures. After fasting for 10 to 12 hours, a blood sample is drawn from a vein in the arm. Then, under medical supervision, the suppression or stimulation procedure is performed. This may involve the use of an intravenous (IV) infusion. Blood samples are then drawn from a vein (or from the IV) at timed intervals.
Sometimes, a single sample of blood is drawn following a fast and rest or after a period of strenuous exercise.
Is any test preparation needed to ensure the quality of the sample?
Follow any instructions you are given. In most cases, you should be fasting. Resting or strenuous exercise for a time period before collection may be required.
Children and pre-teens who are being tested for GH deficiency should be prepared for treatment with sex steroids for a few days prior to testing. Such treatment reduces the number of falsely low GH responses to stimulation. The healthcare practitioner who is ordering the GH testing should provide the child's parents with a prescription for such medications. Some healthcare practitioners will also prescribe propranolol prior to testing to reduce the number of falsely low GH responses to stimulation.
Growth hormone (GH) testing is primarily used to help diagnose growth hormone deficiency and to help evaluate pituitary gland function, usually as a follow-up to other abnormal pituitary hormone test results.
GH testing is also used to detect excess GH and to help diagnose and monitor the treatment of acromegaly and gigantism.
Growth hormone is released in pulses, so a single measurement of the blood level is not normally clinically useful. Therefore, testing for the suppression or stimulation of growth hormone release from the pituitary is usually done.
Other tests that may be done include:
GH suppression testing and IGF-1 testing can also be used to monitor treatment of a pituitary tumor that produces excess GH. If a tumor is located, GH and IGF-1 levels can be measured after the tumor's removal to determine whether the entire tumor was successfully removed. Tests may be ordered at regular intervals for years afterward to monitor GH production and to detect tumor recurrence.
GH stimulation testing is ordered for a child with signs and symptoms of growth hormone deficiency, such as:
Stimulation testing may be ordered for an adult when there are signs and symptoms of growth hormone deficiency and/or hypopituitarism, such as:
Other hormone testing, such as thyroid testing, is typically done first to rule out other conditions that may cause similar symptoms. GH deficiency is rare in children and adults.
GH suppression testing is not commonly ordered but may be done when children or adults show signs and symptoms of GH excess (gigantism and acromegaly).
GH and IGF-1 testing may be ordered at regular intervals for many years to monitor for excess GH.
GH stimulation test
If GH levels are not significantly stimulated during a GH stimulation test (they stay lower than they should) and you have signs and symptoms of growth hormone deficiency (including a low IGF-1 and/or IGFBP3), then it is likely that you have a GH deficiency that your healthcare practitioner may treat.
If your TSH and/or T4 level is abnormal, then that will likely be addressed first as thyroid disorders can cause symptoms similar to growth hormone deficiency. You may also have hypopituitarism and/or a more general decrease in pituitary function. GH testing for GH deficiency should not be performed until your thyroid function has been evaluated. If hypothyroidism is present in a child, it should be treated and the child's growth rate evaluated before GH testing is considered.
If you exercise vigorously and does not experience an increase in GH levels, then you may have a GH deficiency. This finding would need to be followed up with further testing.
Children diagnosed with GH deficiency who have been receiving GH medications during childhood will need to be retested when they have completed growing.
GH suppression test
If your GH levels are not significantly suppressed during a GH suppression test (they stay higher than they should) and you have signs and symptoms of excess GH (gigantism or acromegaly) and a high IGF-1 level (if measured), then it is likely that you are producing too much GH. If a mass is found on an imaging scan (usually MRI), then a pituitary tumor (usually benign) is likely present. If you are being monitored after successful treatment of a tumor, then increases in GH may indicate a recurrence.
Other blood tests that may be used to evaluate pituitary gland function include prolactin, free T4 or total T4, TSH, cortisol, FSH, LH, and/or testosterone. These tests are usually performed prior to GH testing to make sure that they are normal and/or controlled with medication before GH testing is done. For example, hypothyroidism must be treated prior to testing for GH deficiency in children; otherwise, a falsely low GH result may be seen.
Other tests, such as insulin-like growth factor binding protein-3 (IGFBP-3), are sometimes ordered to help evaluate GH production.
Abnormal GH levels can usually be treated once the causes are identified.
It is important to identify GH excess or deficiency as soon as possible for good outcomes. If left untreated, a child with GH deficiency will continue to have a short stature compared to peers. Likewise, the bone growth changes associated with gigantism and acromegaly are permanent.
There can be long-term complications from GH abnormalities. Acromegaly, for instance, can cause colon polyps (increasing your risk of developing colon cancer), diabetes, high blood pressure, and problems with vision. If a pituitary tumor permanently damages pituitary cells, then multiple hormone replacement therapies may be necessary. Increased bone growth may also lead to trapped nerves (carpal tunnel syndrome), arthritis, and weak bones.
Factors that can interfere with GH testing include:
It should be noted that most cases of short stature are not due to GH deficiencies. They can also be related to familial traits, a variety of diseases and conditions, and to other genetic disorders. Rarely, a person may have symptoms associated with GH deficiency but normal or elevated GH levels due to an inherited resistance to GH. In cases of GH resistance, whereas GH levels are high and IGF-1 levels are low.
Besides growth hormone deficiency (GHD), children may be treated with growth hormone replacement if they have:
Growth hormone promotes muscle growth in adults, so it may be taken by some adults as a performance-enhancing drug. Athletes may be tested for GH or IGF-1 when they are being tested for other performance-enhancing drugs. (See the article on Drugs of Abuse for more on sports-related testing.)
Sources Used in Current Review
Growth Hormone (Blood). University of Rochester Medical Center. Available online at https://www.urmc.rochester.edu/encyclopedia/content.aspx?contenttypeid=167&contentid=growth_hormone_blood. Accessed October 2019.
Growth Hormone Stimulation Test (Outpatient). Nationwide Children's Hospital. Available online at https://www.nationwidechildrens.org/family-resources-education/health-wellness-and-safety-resources/helping-hands/growth-hormone-stimulation-test-outpatient. Accessed October 2019.
Growth Hormone Suppression Test. MedlinePlus. Available online at https://medlineplus.gov/ency/article/003376.htm. Accessed October 2019.
Insulin-Like Growth Factor. University of Rochester Medical Center. Available online at https://www.urmc.rochester.edu/encyclopedia/content.aspx?contenttypeid=167&contentid=insulin_like_growth_factor. Accessed October 2019.
Thyroid Function Tests. American Thyroid Association. Available online at https://www.thyroid.org/thyroid-function-tests/. Accessed October 2019.
Tests for Pituitary Tumors. American Cancer Society. Available online at https://www.cancer.org/cancer/pituitary-tumors/detection-diagnosis-staging/how-diagnosed.html. Accessed October 2019.
Growth Hormone Deficiency. National Organization for Rare Disorders. Available online at https://rarediseases.org/rare-diseases/growth-hormone-deficiency/. Accessed October 2019.
Acromegaly. National Institute of Diabetes and Digestive Diseases. Available online at https://www.niddk.nih.gov/health-information/endocrine-diseases/acromegaly. Accessed October 2019.
(June 7, 2013) Growth Hormone. Medscape. Available online at https://emedicine.medscape.com/article/2089136-overview#a2. Accessed October 2019.
Collett-Solber PF, et al. Diagnosis, Genetics, and Therapy of Short Stature in Children: A Growth Hormone Research Society International Perspective. Horm Res Paediatr. 2019 Sep 12:1-14. doi: 10.1159/000502231. [Epub ahead of print]
Melmed S. Pathogenesis and Diagnosis of Growth Hormone Deficiency in Adults. N Engl J Med. 2019 Jun 27;380(26):2551-2562. doi: 10.1056/NEJMra1817346.
Molitch ME, et al., Evaluation and treatment of adult growth hormone deficiency: an Endocrine Society clinical practice guideline. J Clin Endocrinol Metab. 2011 Jun;96(6):1587-609. doi: 10.1210/jc.2011-0179.
Sources Used in Previous Reviews
Thomas, Clayton L., Editor (1997). Taber's Cyclopedic Medical Dictionary. F.A. Davis Company, Philadelphia, PA [18th Edition].
Pagana, Kathleen D. & Pagana, Timothy J. (2001). Mosby's Diagnostic and Laboratory Test Reference 5th Edition: Mosby, Inc., Saint Louis, MO.
Sadovsky, R. (2002 August 6). Are We Ready for Growth Hormone Therapy in Adults? American Family Physician, Tips form other journals [On-line journal]. Available online at http://www.aafp.org/afp/20021115/tips/10.html.
Growth Hormone (Human Growth Hormone, HGH, Somatotropin). ARUP's Guide to Clinical Laboratory Testing (CLT) [On-line test information]. Available online at http://www.aruplab.com/guides/clt/tests/clt_a244.htm.
Growth Hormone Information. The Hormone Foundation [On-line information]. Available online at http://www.hormone.org/learn/growth.html.
(2002 November 12, Updated). Growth hormone no fountain of youth, study suggests. LaurusHealth.com, Today's Headlines [Online information from Reuters Health]. Available online at http://www.laurushealth.com/healthnews/reuters//NewsStory111220023.htm.
Growth hormone tests. Hendrick Health System, AccessMed [On-line information]. Available online at http://www.hendrickhealth.org/healthy/00049860.html.
Ruppe, M., Reviewed (2002 February 23, Reviewed). Growth hormone. Pennhealth.com Health Illustrated Encyclopedia [On-line information]. Available online at http://www.pennhealth.com/ency/article/003706.htm.
Spengler, R. (2001 April 9, Updated). Growth Hormone. LaurusHealth.com, Medical Tests [On-line information]. Available online through http://www.laurushealth.com.
AACE Clinical Practice Guidelines for Growth Hormone Use in Adults and Children. Available for download at http://www.aace.com/clin/guidelines/hgh.pdf.
Bernal-Mizrachi, C., Updated (2001 June 2, Updated). Growth hormone stimulation test. MedlinePlus Health Information [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/003377.htm.
Bernal-Mizrachi, C., Updated (2001 June 1, Updated). Growth hormone suppression test. MedlinePlus [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/003376.htm.
Ruppe, M. (2002 February 23, Updated). Growth hormone. MedlinePlus [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/003706.htm.
Health Resources: Neurosurgery://On-call (2000 February). Understanding Pituitary Tumors. Patient Resources, Disorder of the Month, Pituitary Tumors Feature Article [On-line information]. Available online at http://www.neurosurgery.org/health/patient/detail.asp?DisorderID=19.
Pituitary Overview and Acromegaly. The Hormone Foundation [On-line information]. Available online at http://www.hormone.org/learn/pituitary_1.html.
Anterior Pituitary Function. The Merck Manual of Diagnosis and Therapy [On-line information]. Available online at http://www.merck.com/pubs/mmanual/section2/chapter6/6c.htm.
Bisp, K. (2001 September 13). Testing the integrity of the system - Growth potential and excess. Society for Endocrinology, Endocrine Nurses Training Course [On-line information]. Available online at http://www.endocrinology.org/sfe/training/ent01/ent01_bis.htm.
Pagana, Kathleen D. & Pagana, Timothy J. (© 2007). Mosby's Diagnostic and Laboratory Test Reference, 8th Edition. Mosby, Inc., Saint Louis, MO. Pp. 506 – 510.
Clarke, W. and Dufour, D. R., Editors (2006). Contemporary Practice in Clinical Chemistry. AACC Press, Washington, DC. Grenache, D. and Willis, M., Chapter 31 Hypothalamic, Pituitary, and Gonadal Disorders. Pp. 351 – 363.
Wu, A. (2006). Tietz Clinical Guide to Laboratory Tests, Fourth Edition. Saunders Elsevier, St. Louis, Missouri. Pp. 502 – 510.
Hurd, R. (2006 March 8, Updated). Growth Hormone. MedlinePlus Medical Encyclopedia [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/003706.htm. Accessed on 7/21/07.
Van Voorhees, B. (2006 June 13, Updated). Growth hormone deficiency. MedlinePlus Medical Encyclopedia [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/001176.htm. Accessed on 7/21/07.
Hurd, R. (2006 March 13, Updated). Growth hormone stimulation test. MedlinePlus Medical Encyclopedia [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/003377.htm. Accessed on 7/21/07.
Hurd, R. (2006 March 13, Updated). Growth hormone suppression test. MedlinePlus Medical Encyclopedia [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/003376.htm. Accessed on 7/21/07.
(2007 April). Acromegaly. NIDDK. NIH Publication No. 02-3924 [On-line information]. Available online at http://www.niddk.nih.gov/health/endo/pubs/acro/acro.htm. Accessed September 2007.
Leukemia and Lymphoma Society. Fact Sheet: Long Term and Late Effects of Treatment for Blood Cancers [Online information]. Available for download through http://www.leukemia-lymphoma.org. Accessed October 2007.
William E. Winter, MD, FACB. Lab Tests Online adjunct board member.
Eckman, A. (Updated 2010 April 20). Growth hormone test. MedlinePlus Medical Encyclopedia [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/003706.htm. Accessed October 2010.
(© 1995-2010). Unit Code 8688: Growth Hormone, Serum. Mayo Clinic, Mayo Medical Laboratories [On-line information]. Available online at http://www.mayomedicallaboratories.com/test-catalog/Clinical+and+Interpretive/8688. Accessed October 2010.
Meikle, W. and Roberts, W. (Updated 2010 May). Growth Hormone Deficiency. ARUP Consult [On-line information]. Available online at http://www.arupconsult.com/Topics/GrowthHormone.html?client_ID=LTD. Accessed October 2010.
(© 2010). Growth Disorders Treatment Options, The Hormone Foundation [On-line information]. Available online at http://www.hormone.org/Growth/treatment.cfm. Accessed October 2010.
Savage, M. et. al. (2010 June 23). The Continuum of Growth Hormone–IGF-I Axis Defects Causing Short Stature: Diagnostic and Therapeutic Challenges. Medscape Today from Clin Endocrinol. 2010;72(6):721-728. [On-line information]. Available online at http://www.medscape.com/viewarticle/722763. Accessed October 2010.
Pagana, K. D. & Pagana, T. J. (© 2007). Mosby's Diagnostic and Laboratory Test Reference 8th Edition: Mosby, Inc., Saint Louis, MO. Pp 506-508.
Wu, A. (© 2006). Tietz Clinical Guide to Laboratory Tests, 4th Edition: Saunders Elsevier, St. Louis, MO. Pp 502-503.
Kronenberg, H. et. al. (© 2008). Williams Textbook of Endocrinology, 11th Edition: Saunders Elsevier, Philadelphia, PA. Pp 857-863.
Rosenbloom, Arlan L. Sex Hormone Priming for Growth Hormone Stimulation Testing in Pre- and Early Adolescent Children Is Evidence Based. Horm Res Paediatr 2011;75:78–80.
Updated 2012 April 6). Acromegaly. National Endocrine and Metabolic Diseases Information Service. [On-line information]. Available online at http://www.endocrine.niddk.nih.gov/pubs/acro/acro.aspx. Accessed August 2014.
Topiwala, S. (Updated 2012 May 31). Growth hormone test. MedlinePlus Medical Encyclopedia [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/003706.htm. Accessed August 2014.
Hammami, M. (Updated 2013 June 7). Growth Hormone. Medscape Drugs & Diseases [On-line information]. Available online at http://emedicine.medscape.com/article/2089136-overview. Accessed August 2014.
Diaz-Thomas, A. et. al. (Updated 2014 May 12)). Gigantism and Acromegaly. Medscape Drugs & Diseases [On-line information]. Available online at http://emedicine.medscape.com/article/925446-overview. Accessed August 2014.
Rosenbloom, A. and Guevara-Aguirre, J. (Updated 2014 January 23). Growth Hormone Resistance. Medscape Drugs & Diseases [On-line information]. Available online at http://emedicine.medscape.com/article/922902-overview. Accessed August 2014.
van Bunderen, C. et. al. (2014). Efficacy and Safety of Growth Hormone Treatment in Adults With Growth Hormone Deficiency A Systematic Review of Studies on Morbidity. Medscape News from Clin Endocrinol. 2014;81(1):1-14. [On-line information]. Available online at http://www.medscape.com/viewarticle/827774. Accessed August 2014.
Meikle, A. W. (Updated 2014 January). Growth Hormone Deficiency. ARUP Consult [On-line information]. Available online at http://www.arupconsult.com/Topics/GrowthHormone.html?client_ID=LTD#tabs=0. Accessed August 2014.
(June 7, 2013) Hammami, M. Growth Hormone. Medscape Reference. Available online at http://emedicine.medscape.com/article/2089136-overview#a30. Accessed September 2014.
Eledrisi, MS. Growth Hormone Deficiency. Medscape. Available online at http://emedicine.medscape.com/article/120767-overview. Accessed March 2015.
Kemp, S. Pediatric Growth Hormone Deficiency. Available online at http://emedicine.medscape.com/article/923688-overview. Accessed March 2015.