Testosterone Testing Fact Sheet
Overview of the Test
The sex hormone testosterone is essential for normal sexual development and reproductive functions primarily in men, but also in women. Testosterone levels that are too low or too high can cause a number of health problems.
A testosterone test may be required in men to diagnose erectile dysfunction (ED), infertility, testicular failure (such as from trauma or infection), as well as to diagnose other conditions associated with lower testosterone levels. The test can also assess higher levels of testosterone, which may indicate testicular tumors or a benign prostatic hypertrophy/hyperplasia (BPH), a condition often associated with aging and one that often causes urination problems.
In women, the testosterone test can be used for a number of diagnoses, including infertility, hirsutism (excessive hair growth) and adrenal or ovarian tumors. Higher levels of testosterone in women can indicate polycystic ovary syndrome (PCOS).
In men and women, the test may also help diagnose decreased sex drives.
Evidence and Science behind the Test
In men, Leydig cells in the testes produce the majority of testosterone and the remainder is produced in the adrenal gland. Testosterone production is stimulated by luteinizing hormone (LH) which allows development of the sex organs. Testosterone is also involved in secondary sexual characteristics such as growth of body hair, change in body shape. In women, small amounts of testosterone are produced in the adrenal gland and the ovaries and it is involved in growth and repair of reproductive organs and libido.
The test itself measures total testosterone, or testosterone that is bound to proteins (sex hormone binding globulin – SHBG) in the blood. A slightly different testosterone test assesses free testosterone (between 1% and 4% of total testosterone) in the blood. This may be used if the total testosterone test is unsuitable.
How is it done?
A small blood sample is required from the arm and this is then sent for analysis. Although ranges vary, common result ranges include between 300 and 1000 nanograms per deciliter (ng/dL) for men and 15 to 70 ng/dL for women.
Who Does It?
A doctor, nurse or other qualified professional.
When and How Often?
Testing time may take into account daily variations in testosterone – the highest levels are usually in the early morning. Other hormone tests such as follicle stimulating hormone (FSH) or LH tests may take place alongside.
A testosterone test may be recommended for younger boys who appear to be going into puberty too early.
Tests can start from under $100. It may be covered under some insurance, depending on why the test is required.
Heavy alcohol consumption and liver disease can affect testosterone test results. Hormone treatments (such as estrogen) can lead to decreased testosterone levels, or drugs such as barbiturates and other hormones (i.e growth hormone) can cause higher levels of testosterone. Exercise also increases testosterone levels.
- Bonita Morrow Cavanaugh (2003). Nurse’s Manual of Laboratory and Diagnostic Tests. Fourth Edition. F.A.Davis Company. Philadelphia. Pg 184 – 185
- Testosterone: http://labtestsonline.org/understanding/analytes/testosterone/tab/faq
- Testosterone: http://www.nlm.nih.gov/medlineplus/ency/article/003707.htm
Last reviewed 26/Feb/2014