Several variants of HGH testing like GH serum test, Insulin-like growth factor-1 test, GH suppression test, and GH stimulation test are now available.
Human Growth Hormone Serum Test
The pituitary function test is useful to diagnose a hypothalamic disorder, hypopituitarism, acromegaly, and ectopic growth hormone production by neoplasm.
An HGH Serum Test is ordered to assess pituitary function and help diagnose conditions resulting from the deficiency or overproduction of human growth hormone (HGH) such as hypothalamic disorder, hypopituitarism, acromegaly, and ectopic growth hormone production by neoplasm. The test measures the amount of growth hormone in the blood.
The HGH Serum Test is also commonly referred to as simply GH, HGH, or Human Growth Hormone, as well as Somatotropic Hormone, Somatotropin, or STH. To prepare for this blood test, patients are asked to fast for 10-12 hours and rest for at least 30 minutes prior to collection.
Test results will be available within 2-3 days. Insurance is not required to order this test. Patients also do not need a doctor’s order.
Human growth hormone (HGH) — or simply growth hormone (GH) — is produced by the pituitary gland and secreted into the bloodstream in pulses at various points throughout the day. These pulses range from between 10 and 30 per day and can be strengthened by exercise. As the name suggests, growth hormone is essential for normal growth and development in children.
Although not as active in adults, GH helps regulate bone density, muscle mass, and lipid metabolism, and is important for tissue repair, muscle growth, bone strength, brain function, physical and mental health, energy, and metabolism.
The HGH Serum Test is often ordered along with an IGF-1 Blood Test. Since HGH is secreted in pulses throughout the day, a single test may not accurately show a deficiency or excess. Insulin-like growth factor (IGF) mirrors GH, but IGF is stable throughout the day, and as a result, may be a more accurate indicator of average GH levels.
Insulin-Like Growth Factor (IGF-1) Blood Test
An IGF-1 Blood Test is ordered to help diagnose the cause of growth abnormalities and to evaluate pituitary function.
An Insulin-like Growth Factor Test, or IGF-1 Blood Test, is ordered to help diagnose the cause of growth abnormalities and to assess pituitary function.
The IGF-1 Blood Test is also known as SM-C/IGF-1, Somatomedin-C, and Sulfation Factor. No fasting is required for this test, and results will be delivered within 1-2 days. For patients without insurance, this test is a convenient, low-cost alternative to a traditional doctor’s office visit.
An IGF-1 Blood Test is commonly ordered for patients who have symptoms that indicate insufficient or excess production of human growth hormone (HGH) and IGF-1. Such symptoms include gigantism or slow or delayed growth and development in children, and acromegaly, or decreased bone density and muscle strength in adults.
The test is also used if an underactive pituitary gland is suspected or to monitor patients on HGH therapy.
IGF-1 is a polypeptide hormone produced in the liver and skeletal muscles in response to HGH stimulation. IGF-1, which mediates the actions of HGH and mirrors an excess or deficiency, is essential for the normal growth and development of bone and tissue.
Unlike HGH, IGF-1 levels are stable throughout the day, making it a useful indicator of average HGH levels.
The IGF-1 Blood Test does not diagnose HGH deficiency. Patients may wish to order this test in addition to the HGH Serum Test to provide more information.
To diagnose hypopituitarism, the IGF-1 Blood Test may be ordered alongside other pituitary hormone tests, such as the Adrenocorticotropic Hormone (ACTH) Plasma Test, also known as a Cortisol Blood Test.
Growth Hormone Stimulation Test
The growth hormone (GH) stimulation test measures the ability of the body to produce GH.
How the Test is Performed
Blood is drawn several times. Blood samples are taken through an intravenous (IV) line instead of reinserting the needle each time. The test takes between 2 and 5 hours.
The procedure is done the following way:
- An IV is usually placed in a vein, most often the inside of the elbow or the back of the hand. The site is first cleaned with germ-killing medicine (antiseptic).
- The first sample is drawn early in the morning.
- Medicine is given through the vein. This medicine stimulates the pituitary gland to release GH. Several medicines are available. The healthcare provider will decide which medicine is best.
- Additional blood samples are drawn over the next few hours.
- After the last sample is taken, the IV line is removed. Pressure is applied to stop any bleeding.
How to Prepare for the Test
DO NOT eat for 10 to 12 hours before the test. Eating food can change the test results.
Some medicines can affect the test results. Ask your provider if you should stop taking any of your medicines before the test.
If you will have this test, explain how the test will feel. You may want to demonstrate a doll. The more familiar you are with what will happen and the purpose of the procedure, the less anxiety they will feel.
How the Test will Feel
When the needle is inserted to draw blood, some people feel moderate pain. Others feel only a prick or stinging sensation. Afterward, there may be some throbbing or a slight bruise. This soon goes away.
Why the Test is Performed
This test is most often done to find out whether a growth hormone deficiency (GH deficiency) is causing slowed growth.
Normal Results
Normal results include:
- Normal peak value, at least 10 ng/mL (10 µg/L)
- Indeterminate, 5 to 10 ng/mL (5 to 10 µg/L)
- Subnormal, 5 ng/mL (5 µg/L)
A normal value rules out hGH deficiency. In some laboratories, the normal level is 7 ng/mL (7 µg/L).
Normal value ranges may vary slightly among different laboratories. Some labs use different measurements or test different samples. Talk to your provider about the meaning of your specific test results.
What Abnormal Results Mean
If this test does not raise GH levels, there is a reduced amount of hGH stored in the anterior pituitary.
In children, this results in GH deficiency. In adults, it may be linked to adult GH deficiency.
Risks
There is little risk involved with having your blood taken. Veins and arteries vary in size from one person to another and from one side of the body to the other. Taking blood from some people may be more difficult than from others.
Other risks associated with having blood drawn are slight, but may include:
- Excessive bleeding
- Multiple punctures to locate veins
- Fainting or feeling lightheaded
- Hematoma (blood accumulating under the skin)
- Infection (a slight risk any time the skin is broken)
Medicines that stimulate the pituitary during the test may cause side effects. The provider can tell you more about this.
Growth Hormone Suppression Test
The growth hormone suppression test determines whether growth hormone (GH) production is being suppressed by high blood sugar.
How the Test is Performed
At least three blood samples are taken.
The test is done in the following way:
- The first blood sample is collected between 6 a.m. and 8 a.m. before you eat or drink anything.
- You then drink a solution containing glucose (sugar). You may be told to drink slowly to avoid becoming nauseated. But you must drink the solution within 5 minutes to ensure the test result is accurate.
- The next blood samples are usually collected 1 to 2 hours after you finish drinking the glucose solution. Sometimes they are taken every 30 or 60 minutes.
- Each sample is sent to the laboratory right away. The lab measures the glucose and GH levels in each sample.
How to Prepare for the Test
DO NOT eat anything and limit physical activity for 10 to 12 hours before the test.
You may also be told to stop taking medicines that can affect the test results. These medicines include glucocorticoids such as prednisone, hydrocortisone, or dexamethasone. Check with your healthcare provider before stopping any medicines.
You will be asked to relax for at least 90 minutes before the test. This is because exercise or increased activity can change GH levels.
If you are to have this test done, it may be helpful to explain how the test will feel and even demonstrate it on a doll. The more familiar you are with what will happen and why the less anxiety you will feel.
How the Test will Feel
When the needle is inserted to draw blood, some people feel moderate pain. Others feel only a prick or stinging. Afterward, there may be some throbbing or slight bruising. This soon goes away.
Why the Test is Performed
This test checks for a high level of GH, a condition that leads to gigantism in children and acromegaly in adults. It is not used as a routine screening test. This test is only done if you show signs of increased GH.
Normal Results
Normal test results show a GH level of less than 1 ng/mL. In children, GH levels may be increased due to reactive hypoglycemia.
Normal value ranges may vary slightly among different laboratories. Some labs use different measurements or test different samples. Talk to your provider about the meaning of your specific test results.
What Abnormal Results Mean
If the GH level is not changed and stays high during the suppression test, the provider will suspect gigantism or acromegaly. You may need to be retested to confirm the test results.
Risks
There is little risk involved with having your blood taken. Veins and arteries vary in size from one person to another and from one side of the body to the other. Taking blood from some people may be more difficult than from others.
Risks of having blood drawn are slight, but may include:
- Excessive bleeding
- Multiple punctures to locate veins
- Fainting or feeling lightheaded
- Blood accumulating under the skin (hematoma)
- Infection (a slight risk any time the skin is broken)
Ask any questions you’ve probably got concerning the HGH test to our qualified experts.