Testosterone Test - More Information

This testosterone blood test, also known as a testosterone total & free test, testosterone lab test and testosterone blood test, measures the total and free testosterone blood levels. This lab test builds on the testosterone total test by measuring the free portion of testosterone in addition to the total testosterone in the blood.

Testosterone is a vital hormone in both men and women and abnormal levels can significantly impact quality of life. The reproductive organs make testosterone in both men and women and it is highly involved in different aspects of sexual health. Low testosterone levels can lead to lower sex drive, erectile dysfunction, low energy, low muscle mass and memory loss. Excessively high levels can lead to aggression.

The free component of this testosterone test represents the bioavailable portion of the testosterone in the blood. At any given time, from 1-4% of testosterone in the blood is considered free. To get from where it is made to tissues it exerts its effects on, most testosterone is transported by a carrier protein called sex hormone binding globulin (SHBG) while a small percentage of it circulates unbound. This explains why the free & total testosterone lab test is sometimes ordered with the SHBG test.

When it gets to the target tissues, unbound testosterone can be easily absorbed by cells because it is freely floating around. In contrast, bound testosterone first has to detach from the carrier molecules and then can be absorbed - a process that takes more time. And so, when the term bioavailable, or free, is used in the context of testosterone levels, it represents testosterone that is more readily available for immediate use. Because of the additional information the free measurement of testosterone provides, testosterone total and free levels are frequently measured by people who are undergoing testosterone replacement therapy (TRT) and is why it is measured as part of the TRT blood test panel. Since testosterone replacement can also affect estradiol levels, many people also order the estradiol test with the free and testosterone test.

Free testosterone blood test results provide additional information that can be used for screening or tracking purposes. More specifically, capturing the free testosterone level may be of use when someone is undergoing testosterone replacement, a hypogonadism workup and a hyperandrogenism evaluation in a woman. Additionally, free testosterone is a useful measurement when SHBG levels might be low such as in people with liver and chronic diseases like PCOS, genetic SHBG conditions, and people who are being treated with corticosteroids or estrogen.

To get a testosterone free and total test near you, simply order online and get your blood drawn at the Quest lab that you selected. Once your testosterone total and free lab report is ready, it will be available for download. As can be seen on the testosterone free and total sample lab report, the results are reported as a number and can be compared against the reference range provided by the lab. As can be seen on the total and free testosterone sample report above, the free testosterone level is reported as a separate result in addition to the total testosterone level. In this case, the free testosterone level is 97.2 and can then be compared against the reference range provided by the lab. This particular total and bioavailable testosterone blood test utilizes the LC/MS methodology.

How long does it take to get testosterone total and free lab results? Results for this testosterone blood test are typically available in five business days although results sometimes come back much faster if one is getting their testosterone free and total blood draw at a lab in a big city.