Description: Testosterone Free and Total with Sex Hormone Binding Globulin is a blood test used to detect abnormal levels of testosterone in both male and female patients, and diagnose causes of erectile dysfunction, infertility, virilization, polycystic ovary syndrome, and delayed or early puberty in children.
Also Known As: Total Testosterone Test, Free Testosterone Test, Testosterone Free and Total Test, Sex Hormone Binding Globulin Test
Collection Method: Blood Draw
Specimen Type: Serum
Test Preparation: No preparation required
When is a Testosterone Free and Total with Sex Hormone Binding Globulin test ordered?
When infertility is suspected, or when a man has decreased sex drive or erectile difficulties, a testosterone test may be ordered. Other signs include a lack of beard and body hair, a loss of muscle mass, and the formation of breast tissue. Low total and bioavailable testosterone levels have also been linked to, or caused by, increased visceral fat, insulin resistance, and an increased risk of coronary artery disease.
The test is frequently ordered in conjunction with the FSH and LH tests in males who are experiencing delayed or slow puberty. Although the age at which puberty begins varies from person to person, it usually begins around the age of ten. The following are some of the signs and symptoms of delayed puberty:
- Muscle mass development is delayed.
- Voice not getting lower or a lack of body hair growth
- Growth of the testicles and penis is slowed or delayed.
When a young boy appears to be going through an early puberty with clear secondary sex traits, the test can be ordered. Various malignancies and congenital adrenal hyperplasia can cause early puberty in boys due to elevated testosterone.
When a woman has irregular or no menstrual cycles, is having trouble getting pregnant, or displays masculine traits such as abundant facial and body hair, male pattern baldness, and/or a low voice, testosterone testing may be done. Testosterone levels can rise as a result of malignancies in the ovary or adrenal gland, as well as other illnesses including polycystic ovarian syndrome.
What does a Testosterone Total and Free with Sex Hormone Binding Globulin blood test check for?
In men, testosterone is the primary sex hormone. It's in charge of a man's physical appearance. Although it is thought to be a "masculine" sex hormone, it is found in both men and women's blood. This test determines the amount of testosterone in a person's blood.
Testosterone is primarily produced in the male testicles by unique endocrine tissue called Leydig cells. It's also made by the adrenal glands in both males and females, as well as the ovaries in females in modest amounts.
In males, testosterone promotes the formation of secondary sex characteristics such as penis size, body hair growth, muscle development, and a deeper voice. It is abundant in males during adolescence and adulthood in order to regulate sex drive and preserve muscle mass. Estradiol is the major sex hormone in females, and testosterone is converted to it in women.
The pituitary gland produces luteinizing hormone, which stimulates and regulates testosterone synthesis. Testosterone functions in a negative feedback loop: when testosterone levels rise, LH production falls, slowing testosterone production; lower testosterone levels cause higher LH production, which promotes testosterone production.
Testosterone levels fluctuate throughout the day, increasing in the early morning hours and dropping in the evening. Levels rise after activity and fall as people get older.
About two-thirds of testosterone is attached to sex-hormone binding globulin in the bloodstream, with the remaining one-third bound to albumin. Only a small percentage of testosterone is released into the bloodstream as free testosterone. The bioavailable fraction is the free plus albumin-bound testosterone, which can act on target tissues.
In many circumstances, measuring total testosterone is sufficient information for a healthcare provider. A test for free or bioavailable testosterone may be performed in some circumstances, such as when the level of SHBG is abnormal, as it may more accurately indicate the presence of a medical issue.
SHBG is a liver-produced protein that strongly binds to the hormones testosterone, dihydrotestosterone, and estradiol. SHBG distributes these hormones in the blood as physiologically inactive versions when they are bound. This test examines the amount of SHBG in the blood and is most commonly used to determine whether a person has too much or too little testosterone.
In men, SHBG binds roughly 45 percent to 65 percent of testosterone in the blood, with the rest weakly and reversibly linked to albumin. Only around 2% to 3% of testosterone is accessible to tissues as free testosterone, but testosterone that is weakly linked to albumin is also bioavailable and can be rapidly absorbed by the body's tissues.
In women, a somewhat higher percentage of testosterone is bound to SHBG in the blood than in men. SHBG is important in controlling the quantities of bioavailable male sex hormones and estrogens circulating throughout the body in women. Because SHBG has a stronger affinity for the androgens testosterone and DHT, women with low SHBG may experience signs and symptoms of androgen excess.
A total testosterone test does not differentiate between bound and unbound testosterone; instead, it determines the total amount of testosterone present. In many circumstances, this is sufficient to determine if testosterone production is excessive or inadequate. However, if a person's SHBG level is abnormal, the total testosterone level may not accurately reflect the amount of testosterone available to the person's tissues. When a person's indications and symptoms do not match the results of a total testosterone test, a SHBG test may be conducted.
Lab tests often ordered with a Testosterone Free and Total with Sex Hormone Binding Globulin test:
- Anti-mullerian Hormone
Conditions where a Testosterone Free and Total with Sex Hormone Binding Globulin test is recommended:
- Polycystic Ovary Syndrome
- Hypothalamic disease
- Pituitary disease
- Liver disease
- Eating disorders
- Cushing Syndrome
- Testicular cancer
- Adrenal insufficiency
- Congenital Adrenal Hyperplasia
Commonly Asked Questions:
How does my health care provider use a Testosterone Free and Total with Sex Hormone Binding Globulin test?
In men, women, girls, and boys, testosterone testing is used to identify a variety of problems. Testosterone is the major sex hormone in males, and it is responsible for masculine physical traits. It is produced mostly by the testicles. Although it is thought to be a "male" sex hormone, it is found in both males and females.
The testosterone test can be used to determine whether or not you're experiencing:
- Delayed or early puberty in boys
- In both men and women, sex drive has decreased.
- Men's erectile dysfunction
- Male and female infertility
- Tumors of the testicles in men
- Disorders of the hypothalamus or pituitary gland
- Virilization and hirsutism in girls and women
A testosterone total test is usually used to diagnose a condition. The free and total testosterone test distinguishes between testosterone that is bound to proteins in the blood and testosterone that is not attached to proteins.
About two-thirds of testosterone is tied to SHBG in the blood, with the remaining one-third attached to albumin. Free testosterone circulates in a tiny percentage. Bioavailable testosterone is made up of free testosterone and testosterone bound to albumin, and it can operate on target tissues.
A test for free or bioavailable testosterone may be performed in some circumstances, such as when the level of SHBG is abnormal, as it may more accurately indicate the presence of a medical issue.
Other tests and hormone levels may be performed in conjunction with testosterone testing, depending on the reason for testing. Here are a few examples:
- The sex hormone binding globulin test can be performed to determine whether a man has low testosterone or if a woman has too much testosterone. It can be used in conjunction with other tests to assess a person's sex hormone status.
SHBG is a protein that binds to testosterone, dihydrotestosterone, and estradiol, among other hormones. SHBG distributes these hormones in the blood as physiologically inactive versions when they are bound. Changes in SHBG levels can have an impact on the amount of hormone accessible to the body's tissues.
To assess a person's current hormonal balance, tests for albumin and one or more additional sex hormones, such as prolactin, estradiol, and LH may be conducted.
In order to diagnose the cause of infertility, diminished sex drive, or erectile dysfunction in an adult male, SHBG and total testosterone levels may be ordered. When total testosterone findings are contradictory with clinical symptoms, measuring SHBG in addition to testosterone is extremely beneficial.
Total testosterone in the blood is measured without distinguishing between bound and unbound testosterone; rather, it determines the total amount of testosterone in the blood. In many circumstances, this is sufficient to determine if testosterone production is excessive or inadequate. However, if a person's SHBG level is abnormal, the total testosterone level may not accurately reflect the amount of testosterone available to the body's tissues.
With a simple total testosterone assessment, health practitioners can estimate bioavailable testosterone by measuring SHBG. Because less testosterone is accessible to the body's tissues, increased SHBG in males may be linked to symptoms of low testosterone levels.
Total testosterone should be measured in the initial screening for testosterone deficiency, according to the Endocrine Society's professional standards. If the results are abnormal, the test is repeated the next day. They propose one of the following if repeat readings are low-normal and/or SHBG is abnormal:
The ovaries and adrenal glands produce modest amounts of testosterone in women. Even little increases in testosterone production can throw off the hormone balance, resulting in symptoms including irregular or missed periods, infertility, acne, and excessive face and body hair. These and other signs and symptoms are common in polycystic ovarian syndrome, a disorder marked by an overproduction of male sex hormones. SHBG and testosterone testing may be helpful in detecting and evaluating excess testosterone production and/or decreasing SHBG concentrations, as well as in evaluating women with PCOS.
What does my testosterone test result mean?
Testosterone levels often begin to fall after the age of 30. Testosterone levels may drop more in obese or chronically unwell men, as well as with the use of certain drugs.
Hypogonadism can be caused by a variety of factors, including:
- Pituitary or hypothalamic illness
- Reduced testosterone production in young males can be caused by genetic disorders
- Possible infertility or testicular failure
- Acquired damage to the testes, such as from drinking, physical injury, or viral infections like mumps, reduces testosterone production.
Healthcare practitioners may recommend testosterone replacement therapy to men who have consistently low testosterone levels and associated signs and symptoms. The Food and Drug Administration has not approved testosterone supplements to improve strength, sports performance, or avoid aging disorders. It's possible that using it for these purposes is dangerous.
Increased testosterone levels in men can mean one of several things:
- Tumors of the testicles
- Testosterone-producing tumors in the adrenal glands
- Use of anabolic steroids
- Early puberty in males due to an unknown cause
- Adrenal hyperplasia in toddlers and babies
Testosterone levels in women are typically low. Increased testosterone levels can mean one of the following things:
- Ovarian or adrenal gland tumor
- Adrenal hyperplasia that occurs at birth.
We advise having your results reviewed by a licensed medical healthcare professional for proper interpretation of your results.