Testosterone
At a Glance
Why Get Tested?
To determine if your testosterone levels are abnormal, which may help to explain difficulty getting an erection (erectile dysfunction), inability of your partner to get pregnant (infertility), or premature or delayed puberty if you are male, or masculine physical features if you are female
When to Get Tested?
If you are male and your doctor thinks that you may be infertile or if you are unable to get or maintain an erection; if you are a boy with either early or delayed sexual maturity; if you are a female but have male traits, such as a low voice or excessive body hair, or are infertile or have irregular periods
Sample Required?
A blood sample drawn from a vein in your arm
Test Preparation Needed?
None
The Test Sample
What is being tested?
Testosterone is a steroid hormone (androgen) made by the testes in males. Its production is stimulated and controlled by luteinising hormone (LH), which is manufactured in the pituitary gland. In males, testosterone stimulates development of secondary sex characteristics, including enlargement of the penis, growth of body hair and muscle, and a deepening voice. It is present in large amounts in males during puberty and in adult males to regulate the sex drive and maintain muscle mass. Testosterone is also produced by the adrenal glands in both males and females and, in small amounts, by the ovaries in females. In women, testosterone is converted to oestradiol, the main sex hormone in females.
How is the sample collected for testing?
A blood sample is taken by needle from a vein in the arm.
Is any test preparation needed to ensure the quality of the sample?
No test preparation is needed.
The Test
How is it used?
Testosterone testing is used to diagnose several conditions in men, women and boys. These conditions include:
- delayed or precocious (early) puberty (boys)
- decreased sex drive (men)
- erectile dysfunction (men)
- infertility (men and women)
- excessive body hair, also called hirsutism (women)
When is it requested?
In boys, the test is performed with the FSH and LH tests, if puberty is delayed or slow in developing. Although puberty begins at different times in different individuals, generally by the age of 10 years, there are hormonal and physical manifestations of the onset of puberty. A delay can occur if the testes do not produce enough testosterone or if the pituitary does not produce enough LH.
The test may be performed if a young boy seems to be undergoing a very early (precocious) puberty with obvious secondary sex characteristics, such as an enlarged penis, development of muscle mass and growth of body hair.
In men, the test may be performed when infertility is suspected or if the patient has a decreased sex drive or erectile dysfunction, which can result from low testosterone levels.
In women, testosterone may be measured if a patient has irregular or no menstrual periods, is having difficulty getting pregnant, or appears to have masculine features, such as facial and body hair, male pattern baldness and a low voice. Testosterone levels can rise because of tumours that develop in either the ovary or adrenal gland or because of other conditions, such as polycystic ovarian syndrome (PCOS).
What does the test result mean?
There is great variability in testosterone levels between men and it is normal for testosterone levels to decline as men get older.
However, in males, a decreased testosterone level may indicate hypothalamic or pituitary disease with reduced secretion of LH and FSH, or damage to the testes with reduced production of testosterone. Genetic diseases also can cause decreased testosterone production in young men (Klinefelter’s, Kallman’s, and Prader-Willi syndromes) or testicular failure and infertility (as in myotonic dystrophy, a form of muscular dystrophy). A decreased testosterone level also can indicate impaired testosterone production because of acquired damage to the testes, such as alcoholism, physical injury or viral diseases like mumps.
Increased testosterone levels in males can indicate testicular tumours or use of androgens (also called anabolic steroids). Increased testosterone in boys is usually the cause of early puberty.
In women, increased testosterone levels can indicate polycystic ovary syndrome (PCOS) or an ovarian or adrenal gland tumour.
Is there anything else I should know?
Alcoholism and liver disease in males can decrease testosterone levels. Drugs, including androgens and steroids, can also decrease testosterone levels. Prostate cancer responds to androgens, so many men with advanced prostate cancer receive drugs that lower testosterone levels.
Common Questions
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Article Sources
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