Sex Hormone Binding Globulin SHBG
Also Known As: Testosterone-Estrogen Binding Globulin, SHBG Test, TeBG Test
What is a Sex Hormone Binding Globulin (SHBG) Test?
This test is used to measure sex hormone-binding globulin levels in your blood. SHBG is a protein produced by the liver that attaches itself to the sex hormones found in men and women. These hormones include testosterone (the primary sex hormone in men), dihydrotestosterone or DHT ( another male sex hormone), and estradiol ( a form of estrogen and the main sex hormone in women). SHBG is responsible for transporting the hormones in your bloodstream as their biologically inactive forms. The changes in this protein level can alter the amount of hormones available to be used by your body tissues. Since this test help measure the level of SHBG in your blood, it is also often used to help evaluate your condition for testosterone deficiency or excess.
About 40% to 60% of testosterone in the blood is bound to sex hormone-binding globulin in males. The remainders are weakly and reversibly bound to the albumin. Only 3% of testosterone is directly accessible to the body tissues as free testosterone. However, the testosterone bound to albumin is also bioavailable and is ready to be taken up by the cells and tissues.
As far as women are concerned, SHBG has an integral role in regulating the levels of androgens and estrogens circulating through the body. Since SHBG offers a high affinity for androgens, testosterone, and DHT, women can show symptoms related to excessive androgen.
What Is The Test Used For?
The sex hormone-binding globulin test is often performed to provide additional information regarding testosterone concentration in the bloodstream. In men, doctors use this method to look for testosterone deficiency, but in women, it is used to examine testosterone production.
SHBG, along with testosterone levels, is helpful for an adult man to discover the causes of infertility, low sex drive, erectile dysfunction, and other issues, especially when the total testosterone results are erratic with the clinical symptoms. In women, only a small amount of testosterone hormone is produced by adrenal glands and ovaries. A slight increase in hormone production can modify the balance of hormones and lead to serious problems such as infertility, amenorrhea, hirsutism, and acne. These symptoms are often paired with polycystic ovarian syndrome, a medical condition characterized by excessive androgens like testosterone. In such cases, the sex hormone-binding globulin test helps detect and investigate extra testosterone production and decreased SHBG levels.
Sometimes, hormones like estradiol, prolactin, and luteinizing hormone are also measured to evaluate the existing hormonal balance.
Why And When Do You Need Sex Hormone Binding Globulin Test?
You may need to undergo an SHBG test if you have symptoms related to abnormal testosterone levels. It is especially true if a total testosterone test cannot explain your existing symptoms. It is specially ordered for men with low testosterone levels, but for women, it is performed when there are symptoms of high testosterone levels.
The symptoms of high testosterone levels in women are:
- Fertility problems
- Unexplained weight gain
- Excessive body and facial hair growth
- Deepening of voice
- Menstrual irregularities
Symptoms of low testosterone levels in men include:
- Fertility problems
- Low sex drive
- Difficulty getting an erection
What Kind Of Sample Is Required For The Test?
During the sex hormone-binding globulin test, a healthcare professional will take the sample from a vein in your arm. After a small amount of blood is collected in the test tube or vial, your sample is sent to the laboratory for further analysis.
Do You Need To Prepare For The Test?
You don't need to prepare anything special for this test. However, you must consult your doctor or health care provider regarding your medicines, herbs, and other vitamin supplements that you consume on a routine basis. This also includes medications that don't need any prescription by the doctor.
Are There Any Risks To This Test?
Having a blood test with the needle carries some risks along with it. These risks include infection, bleeding, bruising, and feeling light-headed after the test. When the needle pricks your arm, you might feel a little pain or sting, and afterward, the site may also become sore.
What Do The Test Results Mean?
A high level of sex hormone-binding globulin in the body means that less free testosterone is available to your tissues compared to the ones exhibited by the total testosterone test.
On the other hand, low levels mean that more of total testosterone is bioavailable, but it is not bound to SHBG. This information is quite critical for your doctor as it helps evaluate whether you are showing signs and symptoms of a condition linked to excessive or deficient sex hormone production.
Decrease in sex hormone-binding globulin can be seen with conditions like:
- Polycystic ovarian syndrome
- Type 2 diabetes
- Metabolic syndrome
- Cushing syndrome or excessive use of glucocorticoids like prednisone
- Androgen or anabolic steroid use
- Hypothyroidism or underactive thyroid
Increased SHBG levels can be due to the following:
- Hyperthyroidism or overactive thyroid
- Liver diseases
- Eating disorders like anorexia nervosa
- Decreased sex hormone production in men or Hypogonadism
- Estrogen use in hormone replacement therapy and oral contraceptives
Related Tests: Testosterone Test, Luteinizing Hormone (LH) Test, Follicle-Stimulating Hormone (FSH) Test
Frequently ordered together
Follicle Stimulating Hormone FSH
Luteinizing Hormone LH
Follicle Stimulating Hormone and Luteinizing Hormone-FSH and LH
Anti-Mullerian Hormone AMH-Male
Anti-Mullerian Hormone AMH-Female
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