SHBG

What is SHBG and what role does it play in testosterone levels?

SHBG stands for “Sex Hormone-Binding Globulin”. It is a protein produced by your liver and found in your blood. SHBG binds to sex hormones, such as testosterone and oestrogen, and transports these hormones through your body. Only the portion of testosterone that is not bound to SHBG (known as ‘free’ testosterone) is readily available to act in the body. SHBG therefore plays an important role in regulating how much testosterone is available.

What does a high or low SHBG level mean?

If your SHBG level is high, more testosterone is bound to SHBG, which generally means less free (available) testosterone. If your SHBG level is low, a larger proportion of testosterone may be available as free testosterone. Both situations can affect how you feel and how your body functions.

What symptoms can be associated with abnormal SHBG levels?

A high SHBG level may be associated with symptoms similar to those of a testosterone deficiency, such as fatigue, reduced sex drive, decreased muscle strength and mood changes. A low SHBG level may be associated with signs of higher androgen activity, such as increased body hair or acne. In women, low SHBG levels can, for example, be associated with polycystic ovary syndrome (PCOS).

What can cause SHBG levels to increase or decrease?

Various factors can affect your SHBG level. Elevated SHBG levels may occur with liver disease, pregnancy, the use of certain medications (such as the contraceptive pill), or an overactive thyroid. Low SHBG levels can occur with obesity, type 2 diabetes, the use of certain medications or substances (such as anabolic steroids), and an underactive thyroid.

How does SHBG affect the amount of free testosterone?

SHBG influences how much testosterone in your blood is bound and how much remains available. In general, the higher your SHBG level, the lower the proportion of free testosterone. Conversely, lower SHBG levels are generally associated with a higher proportion of free testosterone. Free testosterone is the fraction that is available to act on tissues in your body.

When should you consider having your SHBG measured?

It may be useful to measure your SHBG if you have symptoms that could indicate a hormonal imbalance, such as unexplained fatigue, changes in libido, irregular periods (in women), or reduced muscle strength. If your doctor suspects that your testosterone levels may be abnormal, measuring SHBG can also help provide a more complete picture.

How is SHBG measured and how should you interpret the result?

SHBG is measured using a finger-prick blood test. At our affiliated ISO-certified laboratory, the amount of SHBG in your blood is determined as part of our testosterone test. The result is compared with the relevant reference values for your age and sex. SHBG is usually interpreted together with other measurements, such as total testosterone, to provide a more complete picture of your hormone levels.

How can abnormal SHBG levels be improved or treated?

Treatment depends on the underlying cause of the abnormal SHBG level. Sometimes an underlying condition, such as a thyroid disorder or obesity, may need to be addressed. Eating a balanced diet, getting enough exercise and maintaining a healthy weight may help. If medication is affecting your SHBG level, your doctor can assess whether any changes are appropriate. In some cases, hormone treatment may be considered, but this should always be discussed with your own doctor.

This article is for informational purposes only and is not a substitute for medical advice from a doctor. If your symptoms persist or you are concerned about your health, always contact your doctor.