SHBG Blood Test
Reviewed
Also called: Testosterone-Estrogen Binding Globulin, TeBG
This test measures the level of sex hormone binding globulin (SHBG) in your blood. SHBG is a protein made mostly in your liver that attaches to sex hormones such as testosterone and estrogen. By binding to these hormones, SHBG helps control how much of them are active in your body. The test is most often used when you have signs of too much or too little testosterone, especially if a total testosterone test did not explain your symptoms. Your provider will usually interpret your SHBG result together with a total testosterone test to estimate how much free testosterone is available for your tissues to use.
Specimen: blood
Why this test may be ordered
- You have symptoms of low testosterone (e.g., low sex drive, difficulty getting an erection, fatigue, loss of muscle mass, fertility problems) and a total testosterone test did not explain them.
- You have symptoms of high testosterone (e.g., too much hair growth on face/body, deepening voice, irregular or absent periods, acne, weight gain, fertility problems) and a total testosterone test did not explain them.
- Your provider suspects a hormonal disorder such as polycystic ovary syndrome (PCOS).
- You are undergoing hormone replacement therapy or treatment for hormone disorders.
- A child shows signs of early puberty.
Preparation and collection
No special preparations are needed. Tell your provider about all medicines, vitamins, and supplements you take, because certain hormone-containing medicines (such as birth control pills, estrogen therapy, or anabolic steroids) can affect SHBG levels. Do not stop any medicine unless your provider tells you to.
A health care professional will take a blood sample from a vein in your arm using a small needle. The procedure usually takes less than five minutes.
There is very little risk to having a blood test. You may have slight pain or bruising at the spot where the needle was put in, but most symptoms go away quickly.
Understanding results
Your provider will usually look at your SHBG blood test results along with the results of a total testosterone test. This helps your provider estimate how much free testosterone is in your blood. The following result patterns are based on the information provided by MedlinePlus.
- Low SHBG level: More of your total testosterone is likely free and available for your body to use. Low levels may be related to hypothyroidism (underactive thyroid), type 2 diabetes or insulin resistance, obesity or being very overweight, overuse of steroid medicines and/or anabolic steroids, Cushing's syndrome, or in females, polycystic ovary syndrome (PCOS). It is also normal for SHBG levels to decrease with older age as the production of sex hormones also decreases. Limitation: This result alone does not diagnose any condition. Your provider will consider your symptoms and other test results to determine the cause. Next step: Routine
- High SHBG level: Less of your total testosterone is available for your tissues to use, so your tissues may not be getting enough testosterone. High levels may be related to liver disease, hyperthyroidism (overactive thyroid), certain eating disorders, use of estrogen-containing medicines (such as hormone replacement therapy or birth control pills) in females, or decreased production of sex hormones in males. Limitation: This result alone does not diagnose any condition. Your provider will consider your symptoms and other test results to determine the cause. Next step: Routine
- An SHBG test alone cannot diagnose polycystic ovary syndrome (PCOS); it can help providers make a diagnosis when paired with other test results.
- Your provider will usually interpret SHBG results together with a total testosterone test to estimate free testosterone levels.
- Certain medicines containing hormones (such as birth control pills, estrogen therapy, or anabolic steroids) can affect SHBG levels.
What to do next
Your provider may order other tests to check if your hormones are in balance with each other. If you have questions about your results, talk with your provider.
- What do my SHBG and total testosterone results together suggest about my free testosterone level?
- Do I need any additional tests to understand my hormone balance?
- How do my current medicines or supplements affect my SHBG level?