Understand your Sex Hormone Binding Globulin (SHBG) Blood Test Results…

This page helps you to understand blood test results for SHBG and gives you the reference range to determine if your lab test results mean that you have high, low or normal SHBG levels. 

We outline the risk factors associated with both raised  and lower SHBG levels.

Reference Ranges for SHBG in men (Sign up to see ranges for women):

Measurement unit Metric Optimal Risk
US Conventional Units nmol/L 10-57 < 10 or > 57
Standard International Units nmol/L 10-57 < 10 or > 57
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What is Sex Hormone Binding Globulin (SHBG)

Sex hormone binding globulin (SHBG) is a protein that is produced by the liver and binds tightly to the hormones testosterone, dihydrotestosterone (DHT), and estradiol (an estrogen).

In men, about 45% to 65% of testosterone in blood is normally bound to SHBG, with about 66-78% being bound in women. A total testosterone test does not distinguish between bound and unbound testosterone but determines the overall quantity of testosterone. If a person’s SHBG level is not normal, then the total testosterone may not be an accurate representation of the amount of testosterone that is available to the person’s tissues [142].

It would be expected to see low SHBG and low free testosterone with low total testosterone, and the focus here should be on strategies to increase testosterone. However if total testosterone is relatively high but free testosterone is low, and SHBG is high, then you may want to talk with your doctor about lowering SHBG.

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Function of Sex Hormone Binding Globulin (SHBG)

SHBG transports male and female sex hormones in the blood as biologically inactive forms. SHBG plays an integral role in regulating the levels of bioavailable male sex hormones (androgens) and estrogens circulating throughout the body [142].

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Risk factors associated with Sex Hormone Binding Globulin (SHBG)

Males – A high SHBG level in relation to the amount of testosterone means that less free testosterone is available to the tissues than is indicated by the total testosterone test and therefore symptoms of low testosterone may occur

Low testosterone may alter certain masculine physical characteristics and impair normal reproductive function. Signs and symptoms may include:

  • Erectile dysfunction
  • Infertility
  • Decrease in beard and body hair growth
  • Decrease in muscle mass
  • Development of breast tissue (gynecomastia)
  • Loss of bone mass (osteoporosis) [135]

Low testosterone can also cause mental and emotional changes. As testosterone decreases, some men may experience symptoms similar to those of menopause in women. These may include:

  • Fatigue
  • Decreased sex drive
  • Difficulty concentrating
  • Hot flashes [135]

Females – SHBG has a higher affinity for the androgens testosterone and DHT and so, in the setting of low SHBG, women may have signs and symptoms related to excess testosterone

High testosterone can result in irregular or no menstrual periods (amenorrhea) or difficulty getting pregnant,

 

 

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Notable variations by demographic group

  • Men have lower levels compared with women
  • Thyroid hormones or estrogens increase SHBG levels
  • SHBG is also produced by placental tissue and therefore values will be elevated during pregnancy
  • In men, there is also an age-related gradual rise. This process can result in bioavailable testosterone levels that are lower than would be expected based on total testosterone measurements alone [143]

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Diet to improve Sex Hormone Binding Globulin (SHBG)

A study in the Journal of Clinical Endocrinology & Metabolism, showed that men who ate more ‘good fats’ for two weeks had less SHBG. As a result, they had higher levels of free testosterone—the only form of testosterone that is ready to work on your tissue.  Sources of good fats include nuts, avocados, eggs, fish oils, olive oil etc.

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Supplements for Sex Hormone Binding Globulin (SHBG)

Researchers examined 100 sedentary men between the ages of 40 and 75 and found that their SHBG had increased 5.7% at the 3-month point and 8.9% after 12 months of regular exercise. This is a positive finding as SHBG increases in line with testosterone in response to exercise, meaning that the amount of both total and free testosterone is increases.

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Exercise to improve Sex Hormone Binding Globulin (SHBG)

Japanese researchers tested the effects of various dietary fats on SHBG, testosterone and nonbound testosterone Fish oil was shown to help reduce serum levels of SHBG in relation to total testosterone.

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Sleep for Sex Hormone Binding Globulin (SHBG)

Further research is required to assess the relationship between sleep and SHBG.