Search For a Provider Facebook Twitter Instagram YouTube ES View the Patient Toolkit

Did You Know?

Free and Total Testosterone

When a person has his or her testosterone levels checked, the results might refer to “free” or “total” testosterone.

Testosterone is usually considered a male sex hormone, since it helps give men their male sex characteristics. For example, a man’s muscle mass, facial hair, and deep voice are all affected by testosterone.

However, both men and women’s bodies produce testosterone. And low testosterone can be a culprit in sexual problems, such as low sex drive.

You might hear your doctor mention “free” testosterone and “total” testosterone.

In men, most testosterone – about 98% in fact – is consider “bound.” This means it’s attached to proteins called albumin and sex hormone binding globulin (SHBG). These proteins help carry the testosterone through the bloodstream so it can be used by different parts of the body.

About 2% of a man’s testosterone is “free.” It is not bound to any proteins. Free testosterone is usually more involved with sexual problems.

Unfortunately, tests of free testosterone are not always reliable. So your doctor might check your total testosterone levels. This measurement includes your bound testosterone and free testosterone together.

Measuring testosterone can be a challenge. Levels are highest in the morning, so most tests are conducted then. However, different labs have different methods for determining what is a “normal” value. Your doctor can explain what your test results mean for you.

The following links can help you learn more about testosterone and the role it plays in sexual health:

Low Testosterone (applies to men)

Women and Testosterone


Print this article or view it as a PDF file here: Free and Total Testosterone


Resources

American Association for Clinical Chemistry (LabTestsOnline.org)

“SHBG”

(Page last modified: February 13, 2012)

http://labtestsonline.org/understanding/analytes/shbg/tab/test

Sexual Medicine Society of North America

“Diagnosing Low Testosterone”

https://www.sexhealthmatters.org/low-testosterone/diagnosing-low-testosterone

TulsaWorld.com

Komaroff, Anthony, MD

“Lab tests for testosterone levels are not always reliable”

(November 18, 2013)

http://www.tulsaworld.com/scene/lab-tests-for-testosterone-levels-are-not-always-reliable/article_da1180c2-0403-52d7-8ba1-873df106a921.html

University of Rochester Medical Center

“Free Testosterone”

http://www.urmc.rochester.edu/encyclopedia/content.aspx?ContentTypeID=167&ContentID=testosterone_free

WebMD

“Testosterone”

(Last updated: April 21, 2010)

http://men.webmd.com/testosterone-15738