Free Testosterone Blood Test
The active hormone driving your energy, libido and muscle.
Free testosterone measures the small fraction of testosterone that circulates unbound to proteins and is therefore immediately available to your tissues. While total testosterone reflects all the hormone in your blood, free testosterone gives a clearer picture of the biologically active portion, which is particularly useful when total testosterone results do not match your symptoms.
This test is for anyone investigating symptoms that may relate to low or high androgen levels, including persistent fatigue, reduced libido, erectile difficulties, loss of muscle mass, low mood, or unexplained changes in body composition. It is also valuable for monitoring hormone therapy, assessing suspected androgen deficiency, and investigating conditions such as polycystic ovary syndrome (PCOS) in women. Because free testosterone can be affected by age, weight, medication and other health conditions, it is often requested alongside other hormone tests for a fuller clinical picture.
Hormones
- Free testosterone: the unbound, biologically active fraction of testosterone, reflecting the amount available to act on target tissues such as muscle, bone, brain and reproductive organs.
Why it matters
Free testosterone can reveal androgen imbalance that total testosterone alone may miss, helping you and your clinician understand the hormonal drivers behind symptoms such as fatigue, low libido, changes in muscle mass, mood or reproductive health. A simple blood sample is all that is needed, and results are interpreted in the context of your symptoms and medical history.
Hormones
- Free testosterone
No special preparation required.
For blood tests, we recommend drinking plenty of water beforehand to ensure smooth sample collection. If you are taking any regular medication, continue to do so unless advised otherwise by your doctor.
Important Clinical Information:
This test is a screening tool to monitor and support your overall health. It does not replace your GP or consultant.
Always discuss your test results, especially any abnormal results, with your GP, who can interpret them in the context of your medical history and overall health.