What Are Growth Hormone Tests?
The pituitary gland, a small pea-sized gland in the skull base, produces many vital hormones that regulate various body functions. Growth hormone (GH), or human growth hormone, is one of the essential hormones produced by the pituitary, responsible for the normal growth of bones and muscles and aids in metabolism. High or low levels of growth hormones can lead to an imbalance in normal development. Therefore, growth hormone tests are done to determine GH levels in the body.
The levels of GH fluctuate throughout the day; therefore, these tests determine the levels of proteins and hormones related to GH production.
What Are the Other Names of Growth Hormone Tests?
The other names of GH tests are the following:
Human growth hormone test.
Growth hormone stimulation test.
Growth hormone suppression test.
What Are the Uses of Growth Hormone Tests?
Growth hormone tests diagnose GH disorders like acromegaly, gigantism, and GH deficiency.
When Are Growth Hormone Tests Advised?
GH deficiency or excess leads to GH disorders. Therefore, the doctor advises growth hormone tests when the patient presents the symptoms.
Acromegaly Symptoms in Adults:
Gigantism Symptoms in Children:
Large hands, feet, and head.
Increase in growth compared to peers.
GH Deficiency Symptoms in Children:
Slow growth when compared to peers.
Short arms and legs.
Lower than average height and weight.
Delayed puberty in girls.
Small penis in boys.
Adults show symptoms of decreased bone and muscle mass.
How to Be Prepared for a Growth Hormone Test?
The following steps need to be followed before going for GH tests:
Fasting: The child is restricted from taking any food or drinks past midnight or at least 12 hours before the test day. However, the child can drink plain water.
Avoid Certain Medications: The doctor must be informed about the child's medicines for other conditions. The doctor may suggest stopping a few drugs based on the test requirement.
Take Steps to Pass the Time: The test takes a few hours to complete. Books, videos, or games help the child to get distracted and co-operate with the procedure.
Avoid Vigorous Exercise: The test results can alter in the case of exercise. Hence, it is recommended to avoid vigorous activity at least ten hours before the test.
Comfortable Dressing: Loose dressing helps the patients to be more comfortable during the test.
What Happens During the GH Test?
The doctor may suggest a GH stimulation test or a GH suppression test based on the symptoms.
1. GH Stimulation Test:
This test diagnoses GH deficiency. A health care worker will collect a blood sample from a vein in the arm. Anesthetic cream is used in children before using the needle to numb the unpleasant sensation. A needle is then inserted, and a small quantity of blood is collected into a vial or a test tube. Then, a medicine that stimulates the pituitary gland to release growth hormone will be administered using an IV (intravenous) line. Blood samples are collected over two hours. The child does not feel pain during the subsequent collection of blood as it is withdrawn through the IV line. Finally, the collected samples are tested to check for an increase in the GH levels.
2. GH Suppression Test:
This test diagnoses GH excess. A health care worker will collect a blood sample from a vein in the arm. A needle is inserted, and a small quantity of blood is collected into a vial or a test tube, after which the patient is asked to drink a solution containing water and glucose. Two more samples are collected after drinking the solution for one to two hours. The blood samples are checked for a decrease in GH levels.
Are There Any Risks to the GH Tests?
Slight redness and pain may be noted at the injection site that usually subsides within a few minutes. The risk of drinking a sugar solution is also negligible.
What Do the Test Results Indicate?
If the growth hormone levels do not rise during the GH stimulation test, it indicates a GH deficiency. The treatment for GH deficiency includes synthetic growth hormone injections given to the child every day at bedtime. The treatment is continued till the child reaches adult height. Most children benefit from the treatment and show an increase in the height of up to 4 inches in the first year of therapy. Early diagnosis and treatment are essential to attain expected growth and development.
Suppose the GH levels do not decrease during the GH suppression test; if the patient has gigantism or acromegaly, the cause is a tumor in the pituitary that produces excess hormones. Surgical removal of the tumor is the indicated treatment. The doctor may suggest a combination of surgery, medications, and radiation in a few cases.
What Are the Other Tests to Determine the GH Levels?
The health care providers may sometimes order a few more tests to determine the GH levels accurately. The tests include:
IGF-1 Test: GH levels in the body are managed by a hormone called IGF-1 (Insulin-like growth factor 1). The levels of IGF-1 remain stable throughout the day, making it easy to diagnose the GH levels more accurately.
IGBP-3 Test: IGBP-3 (Insulin-like growth factor-binding protein 3) acts as a carrier to IGF-1. The test is used to determine GH excess as well as deficiency.
The doctors assess various factors like medical history, surgery, or radiation to the brain to treat other conditions and disorders related to other pituitary hormone insufficiencies to go for GH tests. An early diagnosis and start of therapy can positively impact the overall treatment outcome. Regular check-ups and monitoring of the levels are suggested to control any further fluctuations of the growth hormone.