Growth Hormone Test

Growth hormone (GH) tests are blood tests that check to see if your body is making a normal amount of GH. GH, also known as human growth hormone, is a substance that controls your body’s growth. It also helps control metabolism, the process of how your body uses food and energy. GH is made in the pituitary gland, a small organ at the base of the brain.

In children, GH plays a major role in bone growth, development of muscle mass, and height. In adults, GH affects bone and muscle health. If children or adults have too much or too little GH, it can cause health problems.

GH levels in the blood fluctuate throughout the day depending on your diet and activity levels. So, a standard blood test doesn’t usually provide helpful information about GH levels. Instead, GH levels are usually checked in tests that measure other substances, such as hormones and proteins, that are related to GH production.

Other names: GH test, human growth hormone test, somatropin test, growth hormone stimulation test, growth hormone suppression test

What are they used for?

GH tests are used to diagnose GH disorders, including:

GH deficiency. In children, GH is essential for normal growth and development. A GH deficiency can cause a child to grow more slowly and be much shorter than children of the same age. In adults, GH deficiency can lead to low bone density and reduced muscle mass.

Gigantism. This is a rare childhood disorder that causes the body to produce too much GH. Children with gigantism are very tall for their age and have large hands and feet.

Acromegaly. This disorder, which affects adults, causes the body to produce too much growth hormone. Adults with acromegaly have thicker than normal bones and enlarged hands, feet, and facial features.
The tests may also be used if other tests show a problem with the pituitary gland.

Why do I need a growth hormone test?

Your provider may order a GH test if you or your child has symptoms of a GH disorder.

Symptoms of GH deficiency in children include:

  • Slowed growth rate compared with children of the same age
  • Shorter height, arms, and legs, and lower weight than children of the same age
  • Small penis in males
  • Delayed puberty

Adults with GH deficiency may have symptoms such as fatigue and decreased bone density and muscle mass. However, GH testing isn’t common for adults, as other disorders are much more likely to cause these symptoms.

Symptoms of GH excess (gigantism) in children include:

  • Excessive growth compared with children of the same age
  • Overly large head
  • Larger than normal hands and feet
  • Mild to moderate obesity

Symptoms of GH excess (acromegaly) in adults include:

  • A deep, husky voice
  • Larger than normal facial features such as lips, nose, and tongue
  • Excessive sweating and body odor
  • Thickening of bones
  • Coarse, oily skin
  • Irregular menstrual cycles in women
  • Erectile dysfunction in men

What happens during a growth hormone test?

Your provider may order a GH stimulation or a GH suppression test, depending on whether symptoms show a possible GH deficiency (not enough GH) or a GH excess (too much GH).

A GH stimulation test is used to check for a GH deficiency. During the test:

A healthcare professional will take a blood sample from a vein in your arm, using a small needle.
After the needle is inserted, a small amount of blood will be collected into a test tube or vial.
Your child (or you) will be given a medicine through an IV line that stimulates the pituitary gland to make GH.

More blood samples will be taken over the course of about two hours.
Each sample will be tested to see if GH levels have increased.

A GH suppression test is used to check for a GH excess. During the test:

A healthcare professional will take a blood sample from a vein in your arm, using a small needle.
After the needle is inserted, a small amount of blood will be collected into a test tube or vial.
You or your child will drink a solution that contains water and glucose (sugar).
Two more blood samples will be taken within one to two hours after drinking the solution.
The blood samples will be tested to see if GH levels have decreased.

Will I need to do anything to prepare for this test?

You may need to fast (not eat or drink) for several hours before your test.

Are there any risks to this test?

There is very little risk to you or your child in having a blood test or getting an IV. There may be slight pain or bruising at the spot where the needle was put in, but most symptoms go away quickly. There is no risk to drinking the glucose solution.

What do the results mean?

If GH levels don’t increase to a certain level during a GH stimulation test, it may indicate GH deficiency.

If your child is diagnosed with GH deficiency, he or she may benefit from treatment with GH supplementation. GH supplementation is an injected medicine that contains manufactured human growth hormone. When GH deficiency is diagnosed and treated early, some children can grow several inches in the first year of treatment. Others grow less and more slowly but still benefit from treatment.

If GH levels don’t decrease to a certain level during a GH suppression test, it may mean your child has gigantism or you have acromegaly.

Gigantism and acromegaly are most often caused by a tumor in the pituitary gland, a small organ in the base of the brain that controls many functions, including growth. Treatment for the tumor may include radiation therapy, surgery, and/or medicine. If the disorders were not caused by a tumor, you or your child may need more tests.

Learn more about laboratory tests, reference ranges, and understanding results.

Is there anything else I need to know about a growth hormone test?

Your provider may order other blood tests to help diagnose a GH disorder. These include:

IGF-1 test. IGF-1 is a hormone that helps manage GH in the body. Unlike GH, IGF-1 levels remain stable throughout the day. So, it can be a useful way to find out if your body is making a normal amount of GH.
IGBP-3 test. IGBP-3 is a protein that is the main carrier of IGF-1. This test can help diagnose a GH deficiency or GH excess.

Testosterone Test

The purpose of testosterone testing is to evaluate the amount of the hormone in the blood. Testosterone levels that are outside of a normal range can cause changes in health and physical appearance. Measuring testosterone can help diagnose medical conditions or monitor your response to therapy:

Diagnosis

Doctors may check testosterone levels to determine the cause of your symptoms. Testing can help identify deficiency or an elevated level of testosterone. Tests may be part of assessing if you have health conditions that can affect hormone levels.

Monitoring

This is how doctors follow your health over time. If you have had abnormal testosterone tests, follow-up testing may be used to track your testosterone levels.

Testosterone tests can also monitor the health of transgender men who were assigned female at birth but identify as male. Some transgender men may take hormone therapy to change their physical appearance to match their gender identity. Doctors may monitor testosterone levels in this group of men to ensure testosterone levels are maintained at a certain level.

What does the test measure?

A testosterone test measures the level of the hormone testosterone in the blood.

In men or anyone with a penis, testosterone is produced by the testicles and the adrenal gland, controlling the development of sperm and male sex characteristics. In women or anyone with ovaries, testosterone is produced by the ovaries, the adrenal gland, and other tissues, and it aids in overall growth and development.

Testosterone in the blood can be either bound or free:

Bound testosterone is attached to proteins such as albumin or sex hormone-binding globulin (SHBG). Most testosterone is bound to SHBG.

Free testosterone, the active form, is all the remaining testosterone that is not bound to other substances.
A total testosterone test measures both bound and free testosterone in a blood sample. This is the most common type of testosterone test, and levels are commonly reported in nanograms per deciliter of blood (ng/dL). Less often, a test may be performed for free testosterone, which is reported in picograms per deciliter of blood (pg/dL).

Another less common test is for bioavailable testosterone, which can be used more readily by the body. This is all testosterone that is not bound to SHBG, including free and albumin-bound testosterone. Bioavailable testosterone is also commonly reported in ng/dL.

When should I get this test?

Your doctor may order a testosterone test if you are experiencing symptoms that suggest hormone levels outside of a normal range.

In men or anyone with a penis, a testosterone test may be performed if you have symptoms that suggest a low testosterone level, such as:

  • Early or late onset of puberty
  • Erectile dysfunction
  • Fertility problems
  • Osteoporosis or thinning of the bones
  • Decrease in sex drive

Even if you don’t have symptoms doctors may also evaluate your testosterone levels if you have a health condition that can affect hormone levels. For example, testosterone testing may be performed if you have HIV/AIDS, unexplained bone density loss, infertility, or anemia. If you have undergone certain types of cancer treatment, such as chemotherapy or radiation to the testicles, you may also have your testosterone levels checked.

Doctors may check testosterone levels as part of a diagnostic work-up in women or anyone with ovaries if physical changes suggest a higher-than-normal testosterone level. Changes may include the following:

  • Irregular periods
  • Loss of periods
  • Changes in hair growth patterns
  • Voice changes
  • Skin changes such as oily skin or acne
  • Enlarged clitoris

You may also have testosterone testing if you are a transgender man on masculinizing hormone therapy intended to induce and maintain male sex characteristics. Testing is recommended every three months during the first year of therapy as your dose is adjusted. After that, your doctor may suggest monitoring your testosterone levels one to two times per year.

If you have questions about testosterone testing, talk with your healthcare provider, who can discuss whether this testing is appropriate in your situation.