Sex hormone-binding globulin (SHBG) is an important protein involved in the regulation of our sex hormones and in turn our ability to conceive. So what is a good, or ‘normal’ range for our SHBG levels? And how do we know when ours might be too high or too low? We’ve broken down all you need to know about SHBG levels, including what they mean, why they matter and what to do if you suspect yours might be out of range. Quick facts: What is SHBG? SHBG is an important protein that regulates the amount of testosterone and oestrogen available in the body by ‘binding’ to these hormones—which makes them inactive. This is because to bring about an effect in the body, hormones need to be unbound or free so they can enter cells and bring about their effect. The vast majority of testosterone and oestrogen in our bodies is bound to SHBG and other proteins. SHBG also controls the balance between testosterone and oestrogen, which is also important for the healthy functioning of our menstrual cycles. Why do SHBG levels matter? Because SHBG levels regulate the amount of testosterone and oestrogen available to be used by the body, if our SHBG levels are too high or low, this will have a knock on effect on our levels of both of these sex hormones.  If our SHBG levels are higher, we’ll have less free testosterone or oestrogen available. If our SHBG levels are lower, we’ll have more testosterone and oestrogen available.  Both of these sex hormones have important roles in the regulation of the menstrual cycle, ovulation, libido, energy levels and our mental health. Low SHBG When our SHBG levels are low, our levels of free unbound testosterone and oestrogen can become high. Let’s take a look at some of the symptoms, causes and what can be done to help. Symptoms of low SHBG These symptoms can often mirror those of excess testosterone including: Or excess oestrogen: Causes of low SHBG There is no single cause for abnormal SHBG levels, although increases in insulin, prolactin and androgens have been found to block SHBG production which could be a factor for those with low SHBG levels.  Low SHBG can also be caused by a number of lifestyle factors, certain medical conditions and genetics. Here are several conditions, as well as other factors, that low SHBG has been found to be associated with: How to raise low SHBG If you have low SHBG there are a number of lifestyle changes that may help to increase your levels. These include: High SHBG  On the flip side, when our SHBG levels are too high, our unbound testosterone and oestrogen can become abnormally low. Here are some symptoms, causes and what can be done to reduce high levels of SHBG. Symptoms of high SHBG These symptoms can often mirror those of low testosterone including:  Or low oestrogen: Causes of high SHBG Again, there is no single cause for abnormal SHBG levels, although as we mentioned previously, increases in oestrogen and thyroxine (T4) have been found to increase SHBG production, which could be a factor for those with high SHBG levels. There are also a number of conditions associated with high SHBG which include: How to lower SHBG Dietary changes are the most effective way to lower SHBG levels. Decreasing alcohol consumption, gaining weight if you have a low BHM and following a high-fat, low fibre diet may help decrease levels of SHBG. One study involving 48 premenopausal women showed that maintaining a high-fat, low diet decreased SHBG. However, more clinical studies are required to confirm this association. If the levels are elevated due to contraception use, this will usually return to normal levels once you stop using that contraception. Other possible causes such as type 1 diabetes and an overactive thyroid will need further investigation and will require medication specific to these conditions. SHBG tests Ultimately, if you suspect you may have abnormal levels of SHBG, the only way to definitively get a diagnosis is via a blood test. Because symptoms of abnormal SHBG levels can mimic those of high or low oestrogen and testosterone, your SHBG levels should be tested in tandem these hormones. You can test all of these hormones and more, with a Hertility at-home Hormone and Fertility Test. Resources: