A total testosterone test, also known simply as a testosterone test, is a procedure that measures the levels of testosterone present in the blood of men or women. Doctors can use the test to help diagnose a number of common ailments, including erectile dysfunction, pituitary disorders, male and female infertility and decreased sex drive. In men, normal total testosterone results can vary widely from individual to individual.
The Facts
The testosterone in your bloodstream exists in three distinct states, according to the American Association for Clinical Chemistry's Lab Tests Online. About 1 percent to 4 percent of your testosterone, known as free testosterone, circulates without an accompanying protein. Roughly two-thirds of your remaining testosterone binds itself to a protein called sex-hormone binding globulin, while most of the remaining one-third binds to a blood protein called albumin. A total testosterone test, taken from a simple blood sample, combines the values of all three forms of testosterone into one reading.
Normal Results
Normal male values for total blood testosterone range between 300 and 1,200 nanograms per deciliter, according to U.S. National Library of Medicine's Medline Plus. Female values range between 30 and 95 ng/dL. If you are male, your testosterone level will decrease naturally as you age and skew your results toward lower normal levels, Lab Tests Online reports. Your doctor will take this factor into account when determining a baseline reading for your testing results.
Male Abnormalities
If you are male, a number of factors can decrease your total testosterone below normal levels, according to Lab Tests Online. These include acquired damage to your testicles from sources such as physical injury, alcoholism and viruses; genetic disorders such as Prader-Willi and Kallman's syndromes; and diseases affecting your pituitary gland or hypothalamus. Higher than normal levels of testosterone for men can result from factors including tumors of the testicles or adrenal glands; abnormal increases in thyroid output; use of anabolic steroids and a condition called congenital adrenal hyperplasia.
Female Abnormalities
If you are female, you normally have a small amount of testosterone in your blood to help with your overall hormonal balance, according to Lab Tests Online. Increases from this low level can indicate the presence of conditions including tumors of your adrenal gland or ovaries, polycystic ovarian syndrome and a condition called congenital adrenocortical hyperplasia. You may also experience abnormally high testosterone levels as a result of estrogen therapy. Signs of increased testosterone in women include infertility, absent or abnormal menstruation and excessive body hair.
Considerations
You may also experience increases of your testosterone levels if you use medications such as clomiphene, barbiturates or anticonvulsants, Lab Tests Online reports. In addition to a total testosterone test, you may also receive more detailed tests that can pinpoint your levels of free testosterone, according to Medline Plus.
References
- Lab Tests Online - American Association for Clinical Chemistry: Testosterone - The Test Sample
- Medline Plus - U.S. National Library of Medicine - National Institutes of Health: Testosterone
- Lab Tests Online - American Association for Clinical Chemistry: Testosterone - The Test
- Lab Tests Online - American Association for Clinical Chemistry: Testosterone - Common Questions
