SHBG Test: Don’t Underestimate Its Value For Your Health

There’s a lot of talk about testing your total and free testosterone levels, but not much about the regular use of an SHBG test. After all, why would you want to measure a blood protein to get an idea of your hormone levels? 

Actually, research is gaining ground as to its tremendous impact on your hormone health. Some doctors even recommend carrying out this test regularly to keep an eye on one's risk for certain diseases and disorders.

​So, read on to find out what makes SHBG a crucial marker for your health.

Sex hormone-binding globulin (SHBG) is a carrier protein that defines the amount of unbound (free) sex hormones in your bloodstream. In men, these include testosterone, estrogen, and dihydrotestosterone (DHT). 

SHBG regulates your hormone levels by binding with them and thus negating their bioavailability. With SHBG bound to them, these hormones cannot enter a cell and activate the appropriate receptors and molecular pathways.

The liver is the primary source of SHBG, producing this protein in accordance with the level of certain other hormones in your bloodstream.

For example, SHBG decreases whenever there’s an increase in your insulin, insulin-like growth factor (IGF-1), prolactin, growth hormone, and transcortin. On the other hand, it increases when there’s an abundance of thyroxine and estrogen. 

Due to a process known as aromatization, having too much free testosterone in your blood can actually cause your estrogen levels to increase. In turn, this would lead to a nasty hormonal imbalance and cause a lot of negative effects on your body. 

This is why when your thyroid detects there’s too much free testosterone and estrogen in your blood, it prompts the liver to produce sex hormone binding globulins by releasing thyroid hormone.

However, when there’s too much SHBG in your blood, your body might not have enough bioavailable sex hormones to use up.

It doesn’t matter if your total testosterone is normal or even optimal if your SHBG levels are too high. This would still result in low testosterone as there’s little to no free testosterone available. 

This is why checking yourself with an SHBG test is so important. Knowing your level of this crucial protein can give you a better picture of your hormonal health.

With just the right sex hormone-binding globulin levels, your body’s hormonal balance can be at its optimal state. On the other hand, when too high or too low SHBG can prevent your body from using bioavailable sex hormones for its needs. 

Your SHBG levels are associated with various markers of cardiovascular health. In particular, this makes SHBG a good measure for estimating the body’s risk for cardiovascular disease.

Low levels of the carrier protein coincide with calcification of blood vessels, a common feature of advanced atherosclerosis or arterial plaque. This condition is the primary cause of cardiovascular disease wordlwide.

For men, SHBG levels are even a sign of increased risk of death due to cardiovascular events such as stroke or heart attack.

​A variety of cancers, particularly of the breast and prostate, are stimulated by both estrogen and testosterone. Luckily, SHBG’s nullifying effect on hormones counteracts the effect of these hormones on the proliferation of cancer.

For example, it blocks the estrogen-related mechanisms exploited by breast cancer cells. Eventually, this leads to stopping cancer cell proliferation and promoting the death of cancer cells.

​As for prostate cancer, SHBG determines the severity and invasiveness of tumor growth in the prostate gland. For this reason, an SHBG test is often required to determine if patients should be treated with a more aggressive surgical procedure.

​It’s widely accepted that declining estrogen contributes to bone mineral loss. However, recent research suggests that estrogen does not have anything to do with this decline in bone density.

Likewise, some studies seem to point out that SHBG has an inverse relationship with bone mineral density. Elevated SHBG has been seen to coincide with the increased incidence of vertebrae and peripheral bone fractures borne from osteoporosis.

Polycystic ovarian syndrome (PCOS) is becoming one of the most common and alarming female health issues—and it’s also connected to SHBG. Low SHBG (along with insulin resistance and elevated testosterone production) is usually seen in women suffering from PCOS.

Attempting to increase SHBG and undergoing anti-androgen therapy may have positive effects. But, this metabolic syndrome-like dilemma sometimes requires ovarian drilling, which is a rather invasive process that reduces follicle-stimulating hormone (FSH) secretion.

Obstructive sleep apnea occurs when a person has a blockage in their upper air pathways. Due to this blockage, breathing becomes intermittent which makes it difficult for them to have a good night's sleep. 

One’s SHBG levels are an indicator of sleep apnea due to its disruptive effects on the endocrine system. Lower SHBG correlates with more severe cases of sleep apnea.

Given the difficulty of detecting sleep apnea, it’s good to know that measuring your SHBG levels could reveal whether you’re experiencing it or not. 

​Lower SHBG levels in both men and women indicate increased chances of developing type-2 diabetes. Through an SHBG test, you can determine if you have an increased risk for diabetes, meaning you’d have the chance to follow intervention strategies to prevent its development.

SHBG can be checked through a blood or saliva test. There’s a variety of options available, and some of them even allow you to check your SHBG at the comfort of your home.

Keep in mind when testing that there are certain drugs and substances that can lower or increase your SHBG levels, making the results inaccurate. These include anticonvulsants, metformin, caffeine, exogenous insulin, tamoxifen, progestin, glucocorticoids, oral estradiol, antidepressants, antipsychotics, and H2 antagonists.

​So, before testing for SHBG, it’s best to consult your doctor on how to do so without these drugs affecting your results.

Truth be told, there are many other health concerns linked to SHBG. Cushing’s disease, liver disease, disrupted thyroid-stimulating hormone (TSH) secretion, obesity (including the accumulation of intra-abdominal fat)—SHBG plays a major role in all of these conditions.

As you see, this protein is a fundamental factor to keep track of if you value your health. Taking a test will give you the information you need to make the best decisions for achieving optimal testosterone balance.

There are kits that allow you to conveniently check your hormone and SHBG levels at home—you can easily get your blood or saliva samples and send them to the specified lab for testing. However, these test kits are often limited and lack the precision that a laboratory SHBG test can provide.