Insight into your free testosterone.
Free testosterone is the portion of your testosterone that is not bound to protein and is therefore biologically available. This measurement helps to interpret your total testosterone level, with personal explanation from our doctors.
Also known as: free testosterone, free T
Interpreted by BIG-registered doctors
How Bloodworks works
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Blood draw
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Receive your report
Securely, within a few working days from our physicians
Background
What is free testosterone?
Most of the testosterone in your blood is bound to proteins, mainly to SHBG (sex hormone binding globulin) and to a lesser extent to albumin. Only the unbound portion, the free testosterone, can bind directly to the receptors in your tissues. This is why this fraction is referred to as the biologically available fraction.
When SHBG is abnormal, total testosterone can give a distorted picture. A high SHBG binds more testosterone, so the total value may appear normal while less testosterone is available to the body. A low SHBG can have the opposite effect. Free testosterone helps to interpret this. Because testosterone follows a clear daily rhythm, it is best measured in the morning.
In brief
Biologically available
The fraction not bound to protein
SHBG-dependent
SHBG determines how much stays free
Diurnal rhythm
Highest level in the morning
Complements total
Clarifies a distorted total testosterone
Common reasons to test
When can insight into your Free testosterone be valuable?
Below are some situations in which measuring Free testosterone can provide insight.
With a normal total testosterone but symptoms
When total testosterone falls within the reference range but questions remain, free testosterone can provide additional information.
With an abnormal SHBG
A high or low SHBG affects how much testosterone is bound. Free testosterone shows what remains available.
With questions about energy or libido
Reduced energy or libido is sometimes associated with hormonal changes. A test can provide information.
For sport and muscle recovery
Athletes tracking their hormonal status often measure free testosterone alongside total testosterone and SHBG.
At an older age
As men grow older, SHBG generally rises, which means free testosterone can decline more steeply than total testosterone.
For follow-up of a previous measurement
Those who have tested before can repeat the measurement to track the value over time. Ideally have your blood drawn at a comparable time of day.
What your result means
How do we read your Free testosterone level?
Free testosterone is usually expressed in picomoles per litre (pmol/L). The laboratory provides the reference ranges and takes sex and age into account. The time of the blood draw matters for interpretation, as levels are highest in the morning. A single measurement is not a diagnosis, our doctor places the result in your context.
A low value
A low free testosterone can indicate reduced availability of testosterone, even when total testosterone falls within the laboratory reference range. Possible backgrounds include a raised SHBG, age, lifestyle factors such as sleep, weight, and physical activity, or a condition of the testes, pituitary gland, or thyroid. Our doctor provides context and can indicate whether follow-up measurements such as SHBG, LH, and FSH are worthwhile.
A normal value
A free testosterone within the laboratory reference range gives a reassuring picture of the biologically available fraction. If symptoms persist, they may lie outside this hormone. Our doctor also considers the wider picture, such as thyroid function, iron status, and vitamin B12.
A high value
An elevated free testosterone is seen with a low SHBG and with the use of anabolic steroids or testosterone replacement therapy. In women, an elevated value can occur with polycystic ovary syndrome (PCOS). An elevated value without a clear explanation may be a reason for further investigation.
How we interpret your result
Our doctors assess your free testosterone against the laboratory reference ranges and your personal context, such as age, lifestyle, medication use, and the time of the blood draw. You receive a report in plain language, as a starting point for your own insight or a conversation with your healthcare provider.
Related tests
Often combined with Free testosterone.
A single marker gives one perspective. For a broader picture you can combine Free testosterone with a theme package or related markers.
Frequently asked questions
Everything you want to know
Do I need to fast for a free testosterone test?
Fasting is not required. We do recommend having your blood drawn in the morning, preferably between 7 and 10 o'clock. Testosterone follows a daily rhythm and is at its highest then, which makes the result easier to interpret.
What is the difference between total and free testosterone?
Total testosterone measures all the testosterone in your blood, including the portion bound to SHBG and albumin. Free testosterone measures only the unbound portion, which is directly available to your tissues. When SHBG is abnormal, the two can give a different picture.
Should I also have SHBG measured?
Free testosterone is best interpreted in combination with total testosterone and SHBG. Together they show whether low availability is due to production or to binding by protein. Our doctor can indicate whether additional tests are worthwhile for you.
How is free testosterone determined?
Laboratories determine free testosterone either by direct measurement or by calculating it from total testosterone, SHBG, and albumin. The method used is stated with your result. Because methods differ, it is sensible to have follow-up measurements done at the same laboratory.
Which factors influence my free testosterone?
The time of the blood draw, age, sleep, physical activity, body composition, and stress all play a role. In addition, anything that changes SHBG, such as thyroid function, liver function, insulin sensitivity, and oestrogens, indirectly influences free testosterone.
Is this test also worthwhile for women?
Yes, women also produce testosterone. For questions about hormonal balance, a measurement can be worthwhile. The laboratory applies its own reference ranges per sex and our doctor takes these into account.
How often should I measure free testosterone?
A single measurement is sufficient for initial insight. Those who track the value usually do so annually or after a specific lifestyle change. Ideally have your blood drawn at a comparable time in the morning.
What do I do with my result?
You will receive a PDF report with your value and an explanation from our doctor. What you do with it, such as discussing it with your GP, adjusting your lifestyle, or taking no action, remains entirely your choice.
Ready for insight into your free testosterone?
For €69 you receive your free testosterone level including personal explanation from a doctor, typically within a few working days. No referral required.
Order Free testosterone for €109 →Want to test multiple markers at once?
Combine Free testosterone with other markers via Bloodworks Select. Blood draw costs are waived from €225.
109,-
All-in, blood draw included