Growth Hormone Testing
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Growth Hormone Testing

(GH Testing)

En Español (Spanish Version)

Definition

Growth hormone (GH) testing measures the plasma level of human growth hormone (hGH).

A growth hormone stimulation test measures hormone level after the administration of insulin (insulin tolerance test), GH-releasing hormone, and/or arginine (an amino acid), or GH-releasing peptide. These tests measure the function of the pituitary gland to secrete growth hormone.

A growth hormone suppression test measures the amount of GH that is produced (and how much is suppressed) under conditions of hyperglycemia (high blood sugar) with the administration of a glucose load (oral glucose tolerance test).

Parts of the Body Involved

These tests are conducted intravenously—a needle inserted in a vein in the arm (inside of the elbow) or on the top of the back of the hand.

Reasons for Procedure

Suppression tests are conducted in patients who show symptoms of increased level of human growth hormones. The test can diagnose conditions like gigantism in children and acromegaly (abnormally large bone growth) in adults, which can be caused by elevated levels of human growth hormone.

Stimulation tests are conducted in patients who show symptoms of growth retardation or growth hormone deficiency. The test will diagnose decreased or insufficient levels of human growth hormone that can cause such symptoms.

Growth Retardation

Stunted Growth Child

© 2008 Nucleus Medical Art, Inc.

Risk Factors for Complications

Because the size of veins varies from person to person, drawing blood may be more difficult for certain patients, particularly those with very small veins.

What to Expect

Prior to Procedure

To prepare for the procedure, most patients will need to:

  • Fast for 10-12 hours before the test.
  • Reduce physical activity for 10-12 hours before the test.
  • If instructed by your physician, stop taking regularly prescribed medications before the test.
  • Ninety minutes before the test, rest and relax and avoid physical activity.

Anesthesia

No anesthesia is administered during the procedure.

Description of the Procedure

Suppression Testing

The injection site is cleaned with an antiseptic, and an elastic tie is placed around the upper arm to increase blood flow to the area. Then, a needle is inserted into the vein, and the blood is collected in a vial or syringe attached to the needle. The elastic tie is removed to restore circulation. Once the vials are full, the needle is removed from the skin and the puncture site is covered to stop any bleeding.

The procedure is repeated three times at different intervals. For example, a first sample is taken between 6 am and 8 am. You are then asked to drink a water and glucose solution. Two more blood samples are taken within one to two hours after you have consumed the solution.

Stimulation Testing

Insulin Tolerance Test: The Gold Standard

The injection site is cleaned with an antiseptic, and an elastic tie is placed around the upper arm to increase blood flow to the area. Then, a needle is inserted into the vein, and the blood is collected in a vial or syringe attached to the needle. The elastic tie is removed to restore circulation.

The procedure is repeated five times at different intervals. A first sample for blood glucose, cortisol, and growth hormone is taken between 6 am and 8 am. Then insulin is administered through the IV and blood samples are collected at 30, 60, 90, and 120 minutes later for glucose, cortisol, and growth hormone.

If after 45 minutes the blood sugar has not dropped to a certain level, a repeat dose of insulin is given and the blood sample is collected at 75 minutes and 150 minutes later. If the blood sugar levels falls too low, a high dose of sugar is administered by IV followed by a sugar infusion. Rarely is it necessary to administer steroid IV.

Growth Hormone-Releasing Hormone, Arginine, Growth Hormone-Releasing Peptide

The injection site is cleaned with an antiseptic, and an elastic tie is placed around the upper arm to increase blood flow to the area. Then, a needle is inserted into the vein, and the blood is collected in a vial or syringe attached to the needle. The elastic tie is removed to restore circulation.

The procedure is repeated five times at different intervals. The first sample is taken between 6 am and 8 am. Then, arginine or GH-releasing peptide is administered through the IV for 30 minutes. Once the arginine or GH-relasing peptide has been administered, a GH-releasing hormone is administered intravenously. The last four blood samples are drawn every 30 minutes following both infusions.

After Procedure

GH testing is an outpatient procedure, so patients may return home following the tests. However, some patients may experience bruising, throbbing, or tenderness at the puncture site.

How Long Will It Take?

Depending on the type of test, the procedure typically takes at least three hours.

Will It Hurt?

There may be some minor discomfort when the needle is inserted in the skin, and during the infusions or withdrawals. Some soreness at the puncture site is normal following the procedure, but the procedure is, overall, fairly painless.

Possible Complications

  • Bleeding excessively
  • Fainting, lightheadedness, or dizziness
  • Bruising at the puncture site
  • Infection

If veins are difficult to locate, multiple punctures with the needle may be necessary.

Average Hospital Stay

Since it is an outpatient procedure, patients do not need to be admitted to the hospital.

Postoperative Care

No specific care is required after the procedure. However, if patients feel nauseated or lightheaded, they may need to limit physical activity until they are feeling better. If the puncture site is tender, it should be protected until soreness has subsided.

Many patients may feel very tired after the test, but this is a normal symptom.

Outcome

Outcome is dependent upon the findings of the test and the underlying disease conditions associated with positive test results. While most abnormalities in growth hormone levels can be treated, there are some complications associated with abnormal hormone levels.

Call Your Doctor If Any of the Following Occurs

If you experience symptoms of severe infection, including high fever, drainage of the puncture site, or severe redness or pain in the puncture site, you should call your doctor immediately.

RESOURCES:

The American Association of Clinical Endocrinologists
http://www.aace.com

The Endocrine Society
http://www.endo-society.org

The Pituitary network
http://www.pituitary.org

CANADIAN RESOURCES:

BC Health Guide
http://www.bchealthguide.org/

Health Canada
http://www.hc-sc.gc.ca/index_e.html

References:

Clemmons DR. Value of insulin-like growth factor system markers in the assessment of growth hormone status. Endocrinol Metab Clin North Am. 2007;36:109-29.

Endocrine, metabolism and diabetes tests and procedures: growth hormone test (arginine/clonidine stimulation test). University of Cincinnati Children's Hospital website. Available at: http://www.cincinnatichildrens.org/health/info/endocrine/tests/growth-hormone.htm. Accessed May 28, 2007.

Health Topics A-Z: Growth hormone testing. University of Michigan Health System website. Available at: http://med.umich.edu/1libr/tests/testg09.htm. Accessed May 28, 2007.

Ho KK. H Deficiency Consensus Workshop Participants: Consensus guidelines for the diagnosis and treatment of adults with GH deficiency II: a statement of the GH Research Society in association with the European Society for Pediatric Endocrinology, Lawson wilkins society, European Society of endocrinology, Japan Endocrine Society, and Endocrine Society of Australia. Eur J Endocrinol 2007;157:695-700.

Reiser P. Growth hormone deficiency. Human Growth Foundation website. Available at: http://bchealthguide.org/kbase/topic/medtest/hw7592/descrip.htm. Accessed May 28, 2007.



Last reviewed May 2008 by David Juan, MD

Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.

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