To measure the levels of testosterone and growth hormone in the blood of a patient, specific tests are provided by laboratory workers.
Testosterone Test
Testosterone is the main sex hormone in males. During a boy’s puberty, testosterone causes the growth of body hair, muscle development, and the deepening of the voice. In adult men, it controls the sex drive, maintains muscle mass, and helps make sperm. Women also have testosterone in their bodies, but in much smaller amounts.
This test measures the levels of testosterone in your blood. Most of the testosterone in the blood is attached to proteins. Testosterone that is not attached to a protein is called free testosterone. There are two main types of testosterone tests:
Total testosterone, which measures both attached and free testosterone.
Free testosterone, which measures just free testosterone. Free testosterone can give more information about certain medical conditions.
Testosterone levels that are too low (low T) or too high (high T) can cause health problems in both men and women.
Other names: serum testosterone, total testosterone, free testosterone, bioavailable testosterone
What is it used for?
A testosterone levels test may be used to diagnose several conditions, including:
- decreased sex drive in men and women;
- infertility in men and women;
- erectile dysfunction in men;
- tumors of testicles in men;
- early or delayed puberty in boys;
- excess body hair growth and development of masculine features in women;
- irregular menstrual periods in women.
Why do I need a testosterone levels test?
You may need this test if you have symptoms of abnormal testosterone levels. For adult men, it’s mostly ordered if there are symptoms of low T levels. For women, it’s mostly ordered if there are symptoms of high T levels.
Symptoms of low T levels in men include:
- low sex drive;
- difficulty getting an erection;
- development of breast tissue;
- fertility problems;
- hair loss;
- weak bones;
- loss of muscle mass.
Symptoms of high T levels in women include:
- excess body and facial hair growth;
- deepening of voice;
- menstrual irregularities;
- acne;
- weight gain.
What happens during a testosterone levels 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 may feel a little sting when the needle goes in or out. This usually takes less than five minutes.
Will I need to do anything to prepare for the test?
You don’t need any special preparations for a testosterone levels test.
Are there any risks to the test?
There is very little risk of having a blood test. You may have slight pain or bruise at the spot where the needle was put in, but most symptoms go away quickly.
What do the results mean?
Results mean different things depending on whether you are a man, woman, or boy.
For men:
High T levels may mean a tumor in the testicles or adrenal glands. Adrenal glands are located above the kidneys and help control heart rate, blood pressure, and other bodily functions.
Low T levels may mean a genetic or chronic disease or a problem with the pituitary gland. The pituitary gland is a small organ in the brain that controls many functions, including growth and fertility.
For women:
High T levels may indicate a condition called polycystic ovary syndrome (PCOS). PCOS is a common hormone disorder affecting women of childbearing age. It is one of the leading causes of female infertility.
It may also mean cancer of the ovaries or adrenal glands.
Low T levels are normal, but extremely low levels may indicate Addison’s disease, a disorder of the pituitary gland.
If your results are not normal, it doesn’t necessarily mean you have a medical condition needing treatment. Certain medicines, as well as alcoholism, can affect your results.
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, and 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:
- the 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. But 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:
- 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?
A 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 is 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 in 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.
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.
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.
If you have questions about your results, talk to a healthcare provider for free.