Test library
Unbound Testosterone Test
The free testosterone direct test measures the unbound portion of testosterone in the blood, the fraction available for tissues to use. It helps evaluate deficiency or excess when total testosterone alone does not explain symptoms.
Order Testosterone Level Test
Order online and visit a local collection site, or choose an at-home kit where available. No referral and no insurance required.
Order Testosterone Level Test- Typical turnaround
- 1-3 business days
- Starting price
- From $118
- Results
- Confidential, online
Quick answer
The free testosterone direct test measures the amount of testosterone that is not bound to proteins in the blood. This unbound fraction is available for tissues to use, so it can offer a clearer view of hormone activity than total testosterone alone. It is ordered when symptoms suggest an imbalance or when a total result does not match the clinical picture.
What this test measures
Most testosterone in the blood travels attached to proteins, mainly sex hormone-binding globulin and albumin. Only a small percentage circulates unbound, and this free fraction is considered the biologically active portion. Direct measurement of free testosterone avoids some of the assumptions used in calculated methods, which depend on other values such as SHBG and total testosterone.
The test uses a blood sample, usually collected in the morning when testosterone is highest. The laboratory measures the free hormone directly with a specialized assay. Results are reported as a concentration and compared with a reference range that varies by age and sex. Free testosterone can be useful when total testosterone is borderline or when binding proteins are abnormal.
Clinicians may order this test for symptoms of low testosterone such as fatigue, reduced libido, or mood changes, especially when total testosterone is not clearly low. It can also help evaluate conditions that alter binding proteins. A single result is interpreted with the person's history, and repeat testing may be advised.
- Free testosterone (direct measurement)
- Total testosterone (often paired)
- Sex hormone-binding globulin (SHBG)
- Albumin
- Luteinizing hormone (LH)
- Follicle-stimulating hormone (FSH)
- Bioavailable testosterone (calculated when ordered)
Why people order this test
- Evaluate low testosterone symptoms when total levels appear normal
- Assess hormone activity when binding proteins are abnormal
- Investigate fertility or libido concerns
- Monitor a known hormone condition
- Follow up on an unclear total testosterone result
How to prepare
Collection is usually done in the morning, when testosterone is at its highest. Fasting may be requested if the test is ordered with other panels. Follow the timing instructions provided by the laboratory.
Understanding your results
Results are usually available within one to three business days. The report shows the free testosterone level and its reference range, which varies by age and sex. A qualified healthcare provider interprets the value alongside symptoms and any related tests.
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Frequently Asked Questions
What is free testosterone?
It is the portion of testosterone not attached to blood proteins. This unbound fraction is available for tissues to use and is considered the active form.
How does this differ from a total testosterone test?
A total testosterone test measures all testosterone, bound and unbound. The free test measures only the unbound portion, which can give a different view of hormone activity.
When is the sample collected?
Because levels change through the day, collection is usually done in the morning when testosterone is highest.
Do I need to fast?
Fasting is not usually required unless the test is combined with other panels that call for it. Follow the laboratory's instructions.
Why might a provider order both free and total testosterone?
Ordering both can help clarify hormone activity, particularly when binding proteins are abnormal or a total result does not match the person's symptoms.
Ready to get tested?
Order online and visit a collection site near you, or choose a mail-in kit. No referral and no insurance required.
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Every page on this site is reviewed for clarity, sourcing, and accuracy. We update our library as testing options, collection networks, and accreditation standards change.