What Is the SHBG Blood Test? A Key Hormone Test for Menopause Explained

The SHBG blood test is a valuable tool we use in clinic to assess hormone levels, particularly in the context of menopause.

Table of Contents

What is the SHBG blood test?

SHBG stands for Sex Hormone Binding Globulin, which is a protein produced mainly by the liver. Its role is to bind to certain sex hormones in the blood, mainly testosterone, making it inactive while it is bound. Only the unbound or “free” hormone is biologically active and able to affect the body.

During the transition into menopause, a woman’s hormone levels fluctuate significantly. Oestrogen and progesterone levels gradually decline, while other hormones like testosterone can also shift. Because SHBG binds to these hormones, its levels can influence how much active hormone is actually available in the body.

What causes a high or low SHBG?

SHBG levels themselves can be influenced by a number of factors. Oestrogen tends to increase SHBG, while insulin resistance, obesity, and certain medical conditions can lower it. This means that during menopause, when oestrogen production from the ovaries drops, SHBG levels may also fall. A low SHBG level could result in relatively higher levels of free testosterone, potentially contributing to some of the physical changes women experience in menopause, such as thinning hair or increased facial hair.

Why do we use SHBG in clinic?

The SHBG blood test is especially helpful when evaluating symptoms that may be related to hormone imbalance, such as fatigue, mood changes, low libido, hot flushes, or changes in body composition. These symptoms can sometimes persist even when standard hormone tests appear normal. In these cases, measuring SHBG can help provide a clearer picture.

For example, if a woman has normal total testosterone levels but high SHBG, most of her testosterone may be bound and inactive, leading to symptoms of low testosterone such as reduced libido or low energy. Conversely, if SHBG is low, more testosterone may be free, which could contribute to symptoms like increased body hair or acne.

SHBG and HRT monitoring

In the context of hormone replacement therapy (HRT), SHBG testing can also be useful. Some types of HRT, particularly oral oestrogens, can raise SHBG levels significantly. This may alter the balance of free versus bound hormones in the blood. Monitoring SHBG can help doctors tailor HRT to ensure a woman receives the right dose and type of hormones for her individual needs.

SHBG and PCOS

We use the SHBG to evaluate a woman’s FAI (free androgen index). This will be raised in the context of polycystic ovary syndrome (PCOS). This means that there is more testtosterone hanging around in the blood stream causing the symptoms that women can experience, such as hair on the body and acne.

Final thoughts

Overall, the SHBG test is not typically used on its own but alongside other hormone tests to provide a fuller picture of a woman’s hormonal health. It’s especially valuable when symptoms do not match the results of standard hormone testing, or when HRT is being considered or adjusted. By looking at how much hormone is actually available to the body, it offers deeper insight into the causes of menopause-related symptoms and supports more personalised, effective treatment options.