Sex Hormone Binding Globulin (SHBG) Test:
Sex hormone binding globulin (SHBG) is a protein made by liver that binds to the three sex hormones found in men and women. SHBG transports the hormones; namely, testosterone, dihydrotestosterone, and estrogen in blood. This test measures the level of SHBG in the blood and is ordered when there are signs and symptoms of sex hormone imbalance. It also helps the doctor determine if there is excess or deficient testosterone production.
Factors involved to understand the normal range of Sex hormone binding globulin (SHBG) levels:
The normal range of SHBG concentration in men is 10-57 nmol/L and in women it is in the range of 18-144 nmol/L. Normal ranges vary from laboratory to laboratory.
A high level of SHBG means the protein is attaching to too much testosterone and less free testosterone is available. This indicates less testosterone is available for the tissues.
If the levels of SHBG are too high, it can indicate a problem with testicles or pituitary gland in men. In women, it can indicate a problem with pituitary gland or point to Addison’s disease.
High levels of SHBG are strongly associated with an increased risk of prostate cancer in men. In elderly men, patients with cirrhosis of the liver and hyperthyroidism, SHBG levels are usually found to be high.
Signs and symptoms of sex hormone binding globulin (SHBG) are similar to the signs and symptoms that occur due to low testosterone levels.
In men, the symptoms include:
In women, the symptoms may include:
In both men and women, high SHBG causes decreased sex drive, infertility, reduced bone and muscle mass, and decreased energy levels.
Since, SHBG is mainly produced in liver, abnormal levels of the protein can be due to liver damage. High levels of SHBG are caused by a variety of factors and conditions. These include:
Low levels of SHBG indicate more testosterone is available to the tissues and is not bound to the protein. This may lead to increased availability and higher levels of testosterone in the system.
In men, it can indicate cancer of the testicles or adrenal gland. In women, it can be an indication of polycystic ovarian syndrome (PCOS), acromegaly, obesity, hirsutism, and hypothyroidism.
Low levels of SHBG indicate potentially more free sex hormones in the body. In men, excessive testosterone can cause symptoms such as:
Too much estrogen in men can lead to symptoms such as erectile dysfunction and larger breast tissue.
In women, too much testosterone can cause symptoms such as:
Too much estrogen can lead to irregular periods, mood swings, bloating, and breast tenderness. Low levels of SHBG in women can also cause insulin resistance and obesity.
Conditions that can decrease the levels of SHBG include:
The lower the protein intake, the higher the concentration of SHBG. Protein intake can be an important control of SHBG level. Increasing fiber intake is also associated with higher SHBG. BMI and Insulin negatively influence SHBG concentration. Low-fat diet alone or combined with exercise reduces insulin and BMI levels and increases SHBG levels.
There is a little risk of bruising or experiencing slight pain at the puncture site associated with a simple blood test. Most often, the symptoms go away on their own.
In addition to SHBG test, some other tests are also ordered to evaluate the balance of the hormones. These tests include albumin test to evaluate albumin levels as it is involved in transporting the hormones. Testing for one or more sex hormones may also be suggested. These tests include prolactin test, estradiol, Leutenizing hormone (LH) test, and Follicle Stimulating hormone (FSH) test.
Depending upon the signs and symptoms, additional tests such as testosterone test and estrogen test are ordered to confirm a diagnosis. Testosterone total blood test is ordered when only testosterone test is not sensitive enough to provide accurate results.
The test does not require any special preparations. The test is not performed frequently or routinely and is ordered when the testosterone results are not efficient to determine the cause of infertility, reduced sex drive, erectile dysfunction, irregular menstrual periods, etc. In cases where there is insufficient or excess testosterone, this test is ordered to determine how much testosterone is available for the body.
Pain killers called opiates, medicines for the central nervous system, and recreational drugs, can all affect your test results. Having an eating disorder or engaging in excessive, strenuous exercise can also affect your results. Speak to your healthcare provider for the test.
SHBG levels change throughout life. It is normally high in children of both the sexes. So, the test is often ordered for adults. After puberty, SHBG rapidly decreases in males as compared to females and the levels are usually stable in adulthood and increase in later life. In post menopausal women, the levels decrease as the hormone production decreases. In some cases of deficiency, testosterone or estrogen replacement therapy is used to correct a deficiency.
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