Sex Hormone Binding Globulin

Test Quick Guide

The sex hormone binding globulin (SHBG) test may be used to help evaluate men for low testosterone and women for excess testosterone production. It may be ordered in conjunction with other tests to evaluate the status of your sex hormones.

SHBG and total testosterone levels may be ordered for an adult male to help determine the cause of infertility, a decreased sex drive, or erectile dysfunction. Measurement of SHBG in addition to testosterone is especially helpful when total testosterone results are inconsistent with clinical signs.

In women, small amounts of testosterone are produced by the ovaries and the adrenal glands. Even slight increases in testosterone production can disrupt the balance of hormones and cause symptoms such as irregular or missed menstrual periods, infertility, acne, and excess facial and body hair (hirsutism).

These signs and symptoms and others are often seen with polycystic ovary syndrome (PCOS), a condition characterized by an excess production of male sex hormones (androgens).

About the Test

Purpose of the test

The SHBG test is most commonly used to evaluate low testosterone (possible androgen deficiency) in men. However, it is also used in evaluating women with signs and symptoms suggestive of excess male hormones (androgens).

What does the test measure?

SHBG, a protein produced by the liver, transports the hormones testosterone (an androgen), dihydrotestosterone (DHT) (an androgen), and estradiol (an estrogen) in the blood as biologically inactive forms. Changes in SHBG levels can affect the amount of hormone used by the body’s tissues. This test measures the level of SHBG in the blood and is most often used to help evaluate you for testosterone deficiency or excess.

In men, about 45% to 65% of testosterone in the blood is normally bound to SHBG, with the remainder weakly and reversibly bound to albumin (the main protein in the blood). Only about 2% to 3% of testosterone is immediately available to the tissues as free testosterone. Still, testosterone weakly bound to albumin is also bioavailable and can be readily taken up by the body’s tissues.

Slightly more testosterone is bound to SHBG in the blood (66% to 78%) in women than in men. In women, SHBG plays an integral role in regulating the levels of bioavailable male sex hormones (androgens) and estrogens circulating throughout the body. SHBG has a higher affinity for the androgens testosterone and DHT, and so with the low SHBG, women may have signs and symptoms related to androgen excess.

A total testosterone test does not distinguish between bound and unbound testosterone but determines the overall testosterone level in the plasma. This test is often sufficient to evaluate patients for excess or deficient testosterone production.

But if your SHBG level is not normal, the total testosterone may not accurately represent the amount of testosterone available to your tissues. An SHBG test may be performed when your signs and symptoms do not correlate with the results of a total testosterone test.

When should I get this test?

Currently, the SHBG test is not performed frequently or routinely.

SHBG is ordered primarily when the total testosterone results do not seem consistent with clinical signs and symptoms. In men, these may include infertility, decreased sex drive, and erectile dysfunction; in women, examples are infertility, irregular menstrual periods, and excess facial and body hair.

Finding a Sex Hormone Binding Globulin Test

How can I get a sex hormone binding globulin test?

SHBG testing is usually performed at a doctor’s office or another medical setting like a hospital or lab. The tests are normally ordered by a doctor but may be available without orders from your doctor at a walk-in lab. For example, the test is available without a doctor’s order through Testing.com.

Can I take the test at home?

No, the SHBG test is not currently available as an at-home test.

How much does the test cost?

The cost of an SHBG test will vary depending on factors such as where the test is done and whether you have health insurance. When ordered by a doctor, insurance typically covers the test, although you may have to pay a copay or deductible. Your doctor’s office, lab, and health plan can provide information about any out-of-pocket costs that may be your responsibility.

SHBG tests are available through Testing.com for as little as $67.

Taking a Sex Hormone Binding Globulin Test

The SHBG test requires a blood sample, which is usually taken from your arm in a doctor’s office, health clinic, hospital, or lab.

Before the test

Usually, no special preparation is required for an SHBG test. Yet testosterone is best measured in the morning because, in men, testosterone levels demonstrate diurnal variation with higher levels at that time of day.

During the test

A blood sample is taken from a vein in your arm. The person taking the sample may tie a band around your upper arm and will clean the area where the needle will be inserted into your skin. A small amount of blood is drawn into a tube. You may feel a slight sting when the needle enters your skin.

The process of taking a blood sample usually takes less than three minutes.

After the test

At a doctor’s office or lab, you will be asked to apply gentle pressure to the site with a bandage or a piece of gauze after the needle is withdrawn. This will help stop bleeding and may prevent bruising. Next, the site will be bandaged. You may resume your normal activities following the test.

A blood draw is a very low-risk procedure. You may have slight bruising at the site where the blood sample was taken.

Sex Hormone Binding Globulin Test Results

Receiving test results

The doctor who ordered your SHBG test may share the results with you, or you may be able to access them through an online patient portal. SHBG results are usually available within a few business days. If you use Testing.com, your results will be posted to your account on the site.

Interpreting test results

A high SHBG level means it is likely that less free testosterone is available to your tissues than is indicated by the total testosterone test. And a low SHBG level reveals more of the total testosterone is bioavailable and not bound to SHBG. This information may be important in your overall evaluation when you have signs and symptoms of a condition related to excess or deficient sex hormone production.

Increased SHBG levels may be seen in:

  • Liver disease
  • Overactive thyroid (hyperthyroidism)
  • Eating disorders (anorexia nervosa)
  • Estrogen use (hormone replacement therapy and oral contraceptives)
  • Decreased sex hormone production in men (hypogonadism)
  • Pregnancy

Decreases in SHBG are seen with:

  • Obesity, type 2 diabetes or the metabolic syndrome
  • Polycystic ovary syndrome
  • Underactive thyroid (hypothyroidism)
  • Androgen (“anabolic steroid”) use
  • Cushing’s syndrome or excessive use of glucocorticoids (such as prednisone or dexamethasone)

You may want to ask your doctor the following questions:

  • Are there any other things that my SHBG results might indicate?
  • Do you recommend treatment or monitoring based on my SHBG test results?
  • What follow-up tests will be ordered, and when will they take place?

Sources

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