Testosterone is the most important male hormone. Most of the testosterone in your blood is attached to one of two proteins: albumin and sex hormone binding globulin (
Women’s bodies make and need testosterone as well. Like men, women too, can suffer from a testosterone deficiency. The combination of both your protein-bound testosterone and free testosterone is your “total testosterone,” sometimes also referred to as bioavailable testosterone.
|Gender/Age (y)||Range (pg/mL)|
|0 to 19||Not established|
|20 to 29||9.3−26.5|
|30 to 39||8.7−25.1|
|40 to 49||6.8−21.5|
|50 to 59||7.2−24.0|
|0 to 19||Not established|
Normal free testosterone levels are presented in a range based on age and gender.
What Is the Difference Between Free Testosterone and Total Testosterone?
Most of the time, the testosterone in your blood is “bound” to proteins. But, less frequently, it glides though the blood unbound, as “free testosterone.”
“Total testosterone” represents all the testosterone in your system in any state— both bound to SHBG and albumin, and the testosterone that is “free” or unbound.
If your doctor suspects that you may have low testosterone, you will most likely first be given a simple blood test for your total testosterone. If your total testosterone levels come back as low, your doctor may follow up with a test for your free testosterone, as this will give your healthcare provider a more accurate picture of your ability to produce adequate amounts of testosterone.
Both free and bound testosterone levels decrease as you age.
“Free” testosterone is only that percentage of testosterone that is not bound to any proteins.
How Do We Test for Total Testosterone Levels?
Total testosterone (total T) is measured via a simple blood test. Based upon the results of your total T tests, your doctor may follow up with a free testosterone test.
The following chart illustrates the normal total testosterone levels for men and women by “Tanner Stage” and age. The Tanner Scale breaks down the observable signs of puberty into 5 stages, running from Stage I from about age 10 to Stage V at 15 for boys, and about age 8 to 15 for girls.
|Tanner Stage||Male Testosterone (ng/dL)||Female Testosterone (ng/dL)|
|Adult Male||Adult Female|
|>18 y: 264-916||20 to 49 y: 8−48|
|>49 y: 3−41|
To compare so that you can better understand how variable that “so-called” normal levels of testosterone can be, the following chart gives the “normal” testosterone levels from Quest Diagnostics, another respected testing lab. Quest does not use the Tanner Scale, but rather indicates the normal ranges for males and females by age.
If you compare this chart, to the first chart from LabCorp, you can see how the “normal” ranges differ. These two charts come from two of the most respected testing labs in the country, and yet they have differences. That should help you to understand why it is very hard to pinpoint what is the “normal” total testosterone level for any given person, of any given age. This is precisely why our doctors try to bring every patient to a “target level” that we have found to be optimal for most patients, regardless of age or gender.
Once we determine what your unique optimal level is, we can tailor treatments that will get you in that zone, so you can perform at your personal best, regardless of your age.
What If I am Diagnosed With Low Testosterone?
If your total or free testosterone levels are found to be low, you could benefit from testosterone therapy. We will evaluate the results of your lab tests and your symptoms to determine if you are a candidate for prescription testosterone injections. If you are, you will be prescribed a course of testosterone therapy designed to target the testosterone level that is optimal for you.
Now that you know a little bit more about “free” and “total T,” why not contact us, and find out more about the many life changing benefits of testosterone therapy.
- Jennifer L Shea, Pui-Yuen Wong, Yu Chen
- Alvaro Ocampo M.D.
- David J Handelsman
- L. Antonio, S. Pauwels, M. R. Laurent, D. Vanschoubroeck, I. Jans, J. Billen, F. Claessens, B. Decallonne, Diane De Neubourg, P. Vermeersch, D. Vanderschueren
- Charles Patrick Davis, MD, PhD Medical Editor: Steven Doerr, MD
Free testosterone: clinical utility and important analytical aspects of measurement
‘Total’ vs. ‘Free’ Testosterone: What’s the Difference?
Free Testosterone: Pumping up the Tires or Ending the Free Ride?
Free Testosterone Reflects Metabolic as well as Ovarian Disturbances in Subfertile Oligomenorrheic Women
High and Low Testosterone Levels in Men