What are other Names for this Test? (Equivalent Terms)
- GHRH Blood Test
- GH-RH Blood Test
- Somatocrinin Blood Test
What is Growth Hormone-Releasing Hormone Blood Test? (Background Information)
- Growth hormone promotes development from birth to puberty. It is also essential for the maintenance of metabolism, skeletal muscle, and bone tissue throughout one’s life
- The pituitary gland, located at the base of the brain, releases growth hormone in periodic bursts. Most growth hormone is released during deep sleep
- They hypothalamus of the brain in turn releases hormones that control growth hormone release by the pituitary gland. Growth hormone-releasing hormone (GH-RH) and growth hormone-inhibiting hormone (GH-IH) stimulate and depress growth hormone secretion, respectively
- Growth hormone affects nearly every cell in the body. It causes cells to increase their protein production and their fatty acid metabolism
- The growth-inducing effects of growth hormone are important for adaptation to strenuous demands, such as exercise. Growth hormone also stimulates the replenishment of tissues during everyday wear and tear. The hormone is especially important during childhood development
- Problems with the pituitary gland or GH-RH may cause growth hormone underproduction. This results in stunted growth, abnormal fat distribution, and difficulty regulating blood sugar
- Excessive production of growth hormone, caused by tumors or problems with the regulatory mechanisms, may cause excessive growth. The resulting conditions, though similar, differ depending on the stage in life that a growth hormone overproduction occurred:
- Growth hormone overproduction before puberty results in gigantism. This is marked by extreme lengthening of the skeleton, sometimes causing heights in excess of 8 feet
- Growth hormone overproduction during adulthood results in acromegaly. Because the bones have already reached their maximum length, acromegaly is marked by bone thickening but not lengthening
- The Growth Hormone-Releasing Hormone Blood Test helps measure the levels of growth hormone-releasing hormone in blood. It is used to differentiate between a pituitary tumor and an ectopic secretion of GH-RH
- If GH-RH levels are normal, the result of excessive growth hormone is likely a tumor of the pituitary gland that releases growth hormone without the need for stimulation by GH-RH
- If GH-RH levels are increased, there may be an ectopic tumor of the hypothalamus that secretes GH-RH
What are the Clinical Indications for performing the Growth Hormone-Releasing Hormone Blood Test?
Following are the clinical indications for performing the Growth Hormone-Releasing Hormone Blood Test:
- Following up to an x-ray showing abnormal bone development
- Slow growth in early childhood
- Excessive growth in early childhood
- Disproportionate thickening of the features, particularly the jaw, during adulthood
How is the Specimen Collected for Growth Hormone-Releasing Hormone Blood Test?
Following is the specimen collection process for Growth Hormone-Releasing Hormone Blood Test:
Sample required: Blood
Process of obtaining blood sample in adults:
- A band is wrapped around the arm, 3-4 inches above the collection site (superficial vein that lies within the elbow pit)
- The site is cleaned with 70% alcohol in an outward spiral, away from the zone of needle insertion
- The needle cap is removed and is held in line with the vein, pulling the skin tight
- With a small and quick thrust, the vein is penetrated using the needle
- The required amount of blood sample is collected by pulling the plunger of the syringe out slowly
- The wrap band is removed, gauze is placed on the collection site, and the needle is removed
- The blood is immediately transferred into the blood container, which has the appropriate preservative/clot activator/anti-coagulant
- The syringe and the needle are disposed into the appropriate “sharp container” for safe and hygienic disposal
Preparation required: No special preparation is needed prior to the test.
What is the Significance of the Growth Hormone-Releasing Hormone Blood Test Result?
- A high value (greater than 50 pg/mL) for the Growth Hormone-Releasing Hormone Blood Test may indicate acromegaly caused by GH-RH secretion by the hypothalamus, or ectopic secretion by cancers (in 1% of the cases)
- A normal value (less than 50 pg/mL) for the Growth Hormone-Releasing Hormone Blood Test may point to a tumor of the pituitary gland that releases growth hormone without the need for stimulation by GH-RH
The laboratory test results are NOT to be interpreted as results of a "stand-alone" test. The test results have to be interpreted after correlating with suitable clinical findings and additional supplemental tests/information. Your healthcare providers will explain the meaning of your tests results, based on the overall clinical scenario.
Additional and Relevant Useful Information:
Certain factors interfere with the results of the Growth Hormone-Releasing Hormone Blood Test. These include:
- Eating disorders
Certain medications that you may be currently taking may influence the outcome of the test. Hence, it is important to inform your healthcare provider of the complete list of medications (including any herbal supplements) you are currently taking. This will help the healthcare provider interpret your test results more accurately and avoid unnecessary chances of a misdiagnosis.
The following DoveMed website link is a useful resource for additional information:
Please visit our Laboratory Procedures Center for more physician-approved health information: