Normal free testosterone levels are the most important measurement of testosterone in the body. Some people (and doctors) think that checking total testosterone is the only important aspect of diagnosing Low T, but that is not the case. A person can just as easily have normal total testosterone and low free testosterone levels as he or she can have low total testosterone but normal free testosterone levels (or both being low).

Free testosterone is that which is readily available for use by the body’s tissues. It is unattached to sex hormone binding globulin (SHBG) and albumin so that it can deliver its signals to the testosterone receptor cells throughout the body. Testosterone bound to albumin is also available since this attachment is weak.

When checking free testosterone levels, low numbers indicate a serious problem, especially if total testosterone readings are normal. This tells the doctor that the testosterone attached to SHBG is having a difficult time separating and becoming biologically available for use.

There is also another issue when looking at free testosterone levels – normal is a subjective term. It is easy to think that the minute testosterone levels drop below the “normal” point that the individual is suffering from Low T, but that is not necessarily true. Many people aptly adjust to the changes in hormone production and do not express any symptoms of low testosterone. You can also have someone with normal testosterone levels who does show signs of Low T. That is where the expertise of the hormone specialist here at Kingsberg HRT Clinic is crucial.

Free Testosterone Levels in Men

Although it is important to verify total testosterone levels before initiating hormone replacement treatment, it is even more essential to check free testosterone levels in males. Only when the testosterone is in its free state can it bind to the androgen receptors in organs, the brain, and on the muscles throughout the body.

In regards to free testosterone levels, average is just that – an average of the results of blood tests of many different individuals. Each person has a unique body with its own level of metabolism and hormone production and response. That is why the doctor looks at more than just blood test numbers when diagnosing Low T.

The following chart of free testosterone levels by age in men is just an average for the doctor to use as a guideline when diagnosing Low T:

Age	Free Direct Testosterone Range
Men 20 – 29	9.3 – 26.5 pg/mL
Men 30 – 39	8.7 – 25.1 pg/mL
Men 40 – 49	6.8 – 21.5 pg/mL
Men 50 – 59	7.2 – 24.0 pg/mL
Men over 59	6.6 – 18.1 pg/mL

On occasion, the doctor may want to measure bioavailable testosterone levels, which consists of free testosterone and that which is loosely bound to albumin. For males, this normal range of free and weakly bound testosterone is 40.0 to 250.0 ng/dL.

Free Testosterone Levels in Women

Women are even more susceptible to the effects of declining free testosterone levels than men. The reason for this is that since they start out with such a smaller amount, their bodies register any decrease right away. Measuring free testosterone levels in females is crucial before a doctor prescribes estrogen replacement therapy, as that may not be the right treatment choice.

Normal Free Testosterone Levels	pg/mL Range
Women Over 19 Years of Age	0.0 – 4.2

Bioavailable testosterone is measured in ng/dL instead of pg/mL so do not be confused by the difference in the readings. Oral estrogen may also affect the level of testosterone in the bloodstream.

Bioavailable Testosterone Levels in Women	ng/dL Range
20 to 50 Years of Age Not on Oral Estrogen	0.8 – 10
20 to 50 Years of Age on Oral Estrogen	0.8 – 4.0

No determination of weakly bound and free testosterone levels ng/dl for women over 50 has been established at this time.

It is also important to remember that each lab and many major medical centers have their own guidelines when it comes to total, bioavailable, and free testosterone levels – high, normal, and low. While most of the information provided here is from one particular lab, the breakdown of bioavailable testosterone levels for women based on oral estrogen use is from Mayo Medical Center.

All of these numbers are guidelines. The hormone doctor will look at many other factors when diagnosing Low T. For more information; please contact Kingsberg HRT Clinic direct for a free consultation with a clinical advisor.