What Do Your SHBG Levels Mean?

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:

• Sex Hormone Binding Globulin (SHBG) is an important protein involved in the regulation of our sex hormones in both men and women.
• It is made in the liver and regulates the amount of testosterone and oestrogen available in the body
• When our SHBG levels are low, our levels of free unbound testosterone and oestrogen can become abnormally high, resulting in symptoms associated with high oestrogen and testosterone
• When our SHBG levels are high, our levels of free unbound testosterone and oestrogen can become abnormally low, resulting in symptoms associated with low oestrogen and testosterone
• You can measure your SHBG levels with an at-home Hormone and Fertility Test.

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:

• Excessive body and facial hair (hirsutism)
• Acne
• Increased appetite and weight gain
• Irregular or absent periods
• Voice deepening

Or excess oestrogen:

• Hair thinning/hair loss
• Irregular periods
• Mood changes
• Breast pain

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:

• Obesity: Gaining weight has been shown to have a negative correlation with our SHBG. Simply put, the higher your BMI, the lower your SHBG levels may be. 
• Polycystic Ovarian Syndrome (PCOS): Low SHBG is commonly seen in people with PCOS.
• Hypothyroidism: Having an underactive thyroid can cause your SHBG levels to fall. However, with treatment management, which normally involves thyroid medication, these levels will typically return to their normal range.
• Type 2 diabetes: Type 2 diabetes is associated with elevated insulin levels. People with type 2 diabetes may have lower levels of SHBG compared to non-diabetics. However, the links between type 2 diabetes and SHBG are not yet clear and more research is needed to confirm whether type 2 diabetes causes low SHBG or vice versa. 
• Hyperprolactinemia: Prolactin inhibits SHBG production and so high levels of prolactin can lead to reduced SHBG. However, SHBG levels typically return to normal with treatment management.
• Cushing’s syndrome: Cushing’s syndrome is characterised by abnormally high levels of cortisol. The symptoms of Cushing’s syndrome are similar to the symptoms of PCOS.

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:

• Exercise: Getting our bodies moving helps increase our insulin sensitivity (how our bodies regulate insulin) which has been shown to improve SHBG levels.
• Low sugar, high fibre diet: Reducing our sugar intake and increasing fibre in our diets has also been found to improve SHBG levels.
• Weight loss: Weight loss alone has been shown to increase SHBG in women. Only consider this option if you have an elevated BMI.

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: 

• Decreased sex drive
• Depression and anxiety
• Reduced muscle and bone mass
• Vaginal dryness

Or low oestrogen:

• Depression and anxiety
• Irritability
• Reduced muscle and bone mass
• Vaginal dryness

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:

• Type 1 Diabetes: In type 1 diabetes the pancreas no longer makes insulin, which can lead to higher levels of SHBG.
• Hyperthyroidism: Too many thyroid hormones (like T4) can lead to increased levels of SHBG. Like with hypothyroidism, SHBG levels have been shown to normalise following treatment for hyperthyroidism.
• Alcohol Consumption: Drinking alcohol may increase SHBG. One study showed that consuming more than 2.5 units a day was associated with significantly raised SHBG levels.
• Medication: Hormonal contraception such as the combined oral contraception pill is known to increase SHBG levels while you are using it. This is why they are sometimes used to treat symptoms of high testosterone commonly seen in PCOS.

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:

1. https://pubmed.ncbi.nlm.nih.gov/1827758/ https://www.futuremedicine.com/doi/full/10.2217/bmm-2016-0030
2. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2648802/
3. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3845679/
4. https://pubmed.ncbi.nlm.nih.gov/8150098/
5. https://www.tandfonline.com/doi/full/10.1080/19396368.2017.1410591
6. https://pdfs.semanticscholar.org/3e59/1afbe4114adab1e05e70b3ce5f1cdcd9e529.pdf?_ga=2.208540177.2070196069.1610479116-1773457394.1610479116
7. https://ec.bioscientifica.com/view/journals/ec/2/1/18.xml
8. https://pubmed.ncbi.nlm.nih.gov/6296189/
9. https://pubmed.ncbi.nlm.nih.gov/27192090/
10. https://pubmed.ncbi.nlm.nih.gov/23078574/
11. https://pubmed.ncbi.nlm.nih.gov/8770628/
12. https://pubmed.ncbi.nlm.nih.gov/25281368/
13. https://pubmed.ncbi.nlm.nih.gov/10443669/
14. https://pubmed.ncbi.nlm.nih.gov/8039147/