Testosterone Total

Also known as: Testosterone, Free Testosterone, Bioavailable Testosterone

Why do you need to get tested?

The test is taken to identify atypical testosterone levels in males and females:

In females, excess testosterone can trigger excess body hair (hirsutism), infertility, or polycystic ovary syndrome (PCOS), and masculine physical features (virilization).
In males, it can lead to erectile dysfunction or the inability to impregnant partner (infertility)
In children the test helps identify the reason for early or late puberty, or the reason for genitals that are neither male or female (ambiguous genitalia)

The test is taken to track testosterone levels in transgender individuals undergoing hormone therapy.

Which kind of sample is required?

A blood sample is drawn from a vein in the arm.

Do you need to prepare for the test?

What is being tested in Testosterone Total Blood Test?

Testosterone is found in both males and females but is the primary sex hormone (androgen) in males. Women have a much lower level of testosterone level in comparison to men. Testosterone Total Blood Test shows the level of testosterone in the bloodstream. It is tested as either total testosterone alone or along with bioavailable testosterone or/and free testosterone. Testosterone is produced primarily by testicles in males but is also made by the adrenal glands of both females and males. Ovaries in women also produce minute quantities of testosterone. Testosterone prompts the development of secondary sex characteristics e.g body hair growth, muscle development, deepening of the voice, and enlargement of the penis in males. Testosterone levels are high during puberty and adulthood in males as it controls sex drive and help sustain muscle mass.

Testosterone is changed to estradiol, a sex hormone in women. The production of testosterone is regulated by luteinizing hormone (LH) which is produced in the production is stimulated and controlled by luteinizing hormone (LH), which is made by the pituitary gland. Testosterone works within a negative feedback loop. This means that lower levels of testosterone lead to high LH, which triggers the production of testosterone, while an increase in testosterone levels leads to a decrease in the production of LH, which leads to a reduction in testosterone production. Testosterone levels are diurnal. It is present in its highest concentration in the morning, between 4:00 to 8:00 am, and lowest concentration in the evening, between 4:00 to 8:00 pm. Testosterone levels lower with age and increase with exercise. Two-thirds of testosterone in the body is bound to the protein sex hormone-binding globulin (SHBG) while one-third is bound to the protein albumin, which is in high levels in the bloodstream. Less than 4% of the testosterone circulates the blood as free testosterone. Free testosterone and testosterone bound to albumin can act on target tissues. This is called bioavailable testosterone.

How is the test used?

The testosterone test is often used with other hormone level tests to assess the following issues:

Delayed puberty in boys
Precocious (early) puberty in boys
Decreased sex drive in males and females
Erectile dysfunction in males
Infertility in males and females
Testicular tumors in males
Hypothalamus or pituitary disorders
development of male physical characteristics, such as excess facial and body hair (hirsutism), in girls and women
Genitals that are not clearly male or female (ambiguous genitalia) in infants
Testosterone testing is also used to track testosterone levels in transgender individuals undergoing hormone therapy.

When is the test ordered?

The test is requested by a healthcare professional for men when they have decreased libido, erectile dysfunction, or in cases of infertility. Men with lower levels of testosterone may have no beard and body hair, small testicles, decreased muscle mass, and development of breast tissue (gynecomastia). Boys generally reach puberty between the age of 9-14. In cases of early or late puberty, Testosterone Total Blood Test is ordered alongside FSH and LH blood tests. It is also requested if the following signs and symptoms are observed:

Increase in muscle mass
Deepening of the voice
Growth of body hair and pubic hair
Growth of testicles and penis

The test is taken for women in case of irregular or absent periods, known as amenorrhea, difficulty getting pregnant, or development of masculine characteristics, for example, excess facial and body hair, male pattern baldness, and/or a low voice. In infants, the test is taken in cases where the genitals are not clearly male or female.

What does the test result mean?

Testosterone levels vary with age and stage of maturity in males, and the normal range also varies widely. After age 30, testosterone levels normally begin reducing steadily in males. Low testosterone levels (male hypogonadism) maybe because of:

Chronic diseases such as type 2 diabetes, HIV, liver disease, kidney disease, or autoimmune diseases
Physical injury or trauma to the testicles
Viral diseases like mumps
Chemotherapy or radiation therapy
Removal of testicles to treat cancer
Use of medications such as antidepressants or narcotic pain medications
Hypothalamic or pituitary disease
Genetic diseases that can cause decreased testosterone production in young men (e.g., Klinefelter, Kallman, and Prader-Willi syndromes) or testicular failure and infertility (e.g., myotonic dystrophy, a form of muscular dystrophy)

Increased testosterone levels in males suggest:

Testicular tumors
Adrenal tumors that are producing testosterone
Use of anabolic steroids, which contain synthetic testosterone
Early puberty of unknown cause in boys
Congenital adrenal hyperplasia in babies and children

Females: Women generally have low levels of testosterone in comparison to men, and the normal range for women also varies from that of men. High testosterone levels can suggest the following :

Polycystic ovary syndrome (PCOS)
Ovarian tumor or adrenal gland tumor
Congenital adrenal hyperplasia
Testosterone exposure from physical contact with someone around them using testosterone topical products

Related Tests: Follicle-stimulating Hormone (FSH), Luteinizing Hormone (LH), Sex Hormone Binding Globulin, (SHBG), DHEAS, Estrogens, Semen Analysis, Anti-Müllerian Hormone, Androstenedione

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