Testosterone Test
At a Glance
Why Get Tested?
To find out if testosterone levels are abnormal in a male or female patient. Measurement may help to explain why a man has difficulty in getting an erect penis (erectile dysfunction), the inability of your partner to get pregnant (infertility), premature or delayed puberty, or masculine physical features if you are women. In a women it is used to investigate polycystic ovarian syndrome (PCOS).
When to Get Tested?
If you are man 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 (hirsutism), or are infertile or have no periods or if they are irregular
Sample Required?
A blood sample taken from a vein in your arm
The Test Sample
What is being tested?
Testosterone is a steroid hormone (androgen) made by the testes in males. The production of testosterone is stimulated and controlled by luteinising hormone (LH), which is manufactured in the pituitary gland.
In men, testosterone stimulates the enlargement of the penis, growth of body hair, muscle development, and a deepening voice. It is present in large amounts in boys during puberty and in men to regulate the sex drive and maintain muscle mass.
In women testosterone levels are about one tenth of those in men. Testosterone is produced both in small amounts from the ovary and by conversion from other weak androgens in the body.
Testosterone is also produced by the adrenal glands in both men and women.
How is the sample collected for testing?
A blood sample is taken by needle from a vein in the arm.
There is no preparation e.g. fasting required for this test.
NOTE: If undergoing medical tests makes you or someone you care for anxious, embarrassed, or even difficult to manage, you might consider reading one or more of the following articles: Coping with Test Pain, Discomfort, and Anxiety, Tips on Blood Testing, Tips to Help Children through Their Medical Tests, and Tips to Help the Elderly through Their Medical Tests.
Another article, Follow That Sample, provides a glimpse at the collection and processing of a blood sample and throat culture.
The Test
How is it used?
Testosterone testing is used to diagnose several conditions in men, women, and boys. These conditions include:
Boys
Men
Women
Men and women
When is it requested?
In boys, the testosterone is measured 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, deepening voice 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 (amenorrhoea), 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 in men and it is normal for testosterone levels to fall as men get older.
In males, a low testosterone level may be due to hypothalamic or pituitary disease with reduced production of LH and FSH, or damage to the testes with reduced production of testosterone. Genetic diseases 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. Use of most anabolic steroids also causes a decrease in testosterone levels.
Increased testosterone levels in males can indicate testicular tumours . 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 reduce testosterone levels. Prostate cancer responds to androgens, so men with advanced prostate cancer may receive drugs that lower testosterone levels.
Common Questions
Ask a Laboratory Scientist
Article Sources
NOTE: This article is based on research that utilizes the sources cited here as well as the collective experience of the Lab Tests Online Editorial Review Board. This article is periodically reviewed by the Editorial Board and may be updated as a result of the review. Any new sources cited will be added to the list and distinguished from the original sources used.
