SHBG blood test

This test measures the levels of SHBG in a sample of your blood. SHBG stands for sex hormone binding globulin. It is a protein that is produced primarily in your liver. It binds (attaches) to the sex hormones in your blood.

SHBG helps control the amount of sex hormones that are actively present in your body. When the SHBG protein binds to sex hormones, your tissues cannot use these hormones. Your tissue can only use sex hormones that are “free,” meaning they're not attached to proteins, like SHBG.

A SHBG test is usually done if you have signs and/or symptoms of an excess or lack of the sex hormone testosterone. Testosterone is known as a “male” sex hormone, but women have testosterone in smaller amounts.

In adult men, testosterone controls sexual desire, maintains muscle mass, and helps produce sperm. In adult women, testosterone is important for healthy organs and the growth of bones and muscles. Measuring SHBG levels can provide information about how much testosterone is active in your body's tissues.

Other names: Testosterone-Estrogen Binding Globulin, TEbG

The SHBG test is most often used to gather information about how testosterone works in the body to:

• Adult men who have symptoms that may be caused by low testosterone
• Adult women who have symptoms that may be caused by too high testosterone

In general, your health care provider will order a blood test for total testosterone first. This test provides a measure of All testosterone in your blood sample, which includes free testosterone as well as protein-bound testosterone But this test doesn't show how much of your testosterone is free for your body to Use it. So, you could have symptoms due to free testosterone that is too low or too high even when your total testosterone level is normal.

If your total testosterone level doesn't explain your symptoms, your provider may order a SHBG blood test to help determine how much free testosterone you have. SHBG and total testosterone tests can also be done at the same time.

You may need this test if you have signs and/or symptoms of abnormal testosterone levels, especially if the results of a total testosterone test don't explain your symptoms.

If you are a man, you may need this test if you have symptoms of low testosterone levels, including:

• Low libido
• Difficulty getting an erection
• Fertility problems

If you are a woman, you may need this test if you have symptoms of high testosterone, including:

• Too much hair on the face and body
• Deepening of the voice
• Have irregular periods or no periods at all
• Acne
• Weight gain
• Fertility problems

You don't need any special preparations for a SHBG test.

There is very little risk in taking a blood test. You may feel a slight pain or bruise where the needle was inserted, but most symptoms go away quickly.

Your provider will usually review the results of your SHBG blood test along with the results of a total testosterone test. This helps your provider estimate how much free testosterone is in your blood.

If your SHBG levels are too low, this means that more of your total testosterone is likely available for your body to use.

Low levels of SHBG may be linked to:

• Hypothyroidism
• Type 2 diabetes
• Obesity or significant overweight
• Overuse of steroid medications and/or anabolic steroids
• Cushing's syndrome
• In women, polycystic ovary syndrome (PCOS).

It is also normal for SHBG levels to decrease with age because the production of sex hormones also decreases.

If your SHBG levels are too high, this probably means that a smaller portion of your total testosterone is free testosterone available to your tissues. As a result, your tissues may not get enough testosterone.

High levels of SHBG may be linked to:

• Liver disease
• Hyperthyroidism
• Eating disorders
• In women, use of estrogens in medicine, such as:
  • Hormone replacement therapy
  • Contraceptive pills
• In men, reduced production of sex hormones

Your provider may order additional tests to check if your hormones are in balance with each other. If you have questions about your results, talk to your provider.

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

A SHBG test may be used with other tests to help diagnose precocious puberty in children. Normally, SHBG levels are high in all children. High levels prevent sex hormones from affecting body tissue. If SHBG levels are low, children may start puberty too early.

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