Free Tri-iodothyronine (Free T3)
Also known as: Free T3, FT3
Not near Sutton Coldfield? Have this blood test anywhere in the UK
We offer blood tests across the UK through our partner network: have your sample taken at The Vesey or at a partner clinic near you, anywhere in the UK and Ireland. A Health Advisor books it for you on a free 15-minute call, and your results come back to The Vesey for our GPs to review.
Free tri-iodothyronine (free T3) is the unbound, active form of T3, the more metabolically active thyroid hormone. At The Vesey in Sutton Coldfield, Free Tri-iodothyronine is available within 18 private blood test panels, with clinician-reviewed results. This page is educational and does not replace personalised medical advice.
What Free Tri-iodothyronine measures
Free tri-iodothyronine (free T3) is the unbound, active form of T3, the more metabolically active thyroid hormone. Much of the body’s T3 is produced by converting T4 in the tissues.
Why it is tested
Free T3 is sometimes measured together with TSH and free T4 to give additional detail about thyroid hormone status. It is included in several broader thyroid and endocrine panels.
Tests that include Free Tri-iodothyronine at The Vesey
Guide prices are read from the current Vesey catalogue and confirmed at booking.
Thyroid
Guide price from £148
Fertility
Guide price from £210
Standard Screen Plus (Female)
Guide price from £210
Standard Screen Plus (Male)
Guide price from £210
Tired All The Time?
Guide price from £217
Fertility + STI
Guide price from £220
12 further Vesey panels include Free Tri-iodothyronine. See all blood test panels →
Related biomarkers
Other markers in the thyroid group:
Frequently asked questions
How does T3 differ from T4?
T3 is the more active thyroid hormone at the tissue level, while T4 acts partly as a reservoir that is converted into T3. Both are interpreted together with TSH.
This page is for general education and information only. It is not medical advice, a diagnosis, or a recommendation for any specific test or treatment, and it does not include reference ranges, which are laboratory-dependent and interpreted by a clinician. Guide prices are indicative and confirmed at the time of booking. Always discuss your health and any test results with a qualified clinician. In an emergency call 999; for urgent non-emergency advice call NHS 111.
Private blood testing in Sutton Coldfield
Clinician-reviewed results. No GP referral needed.
Not sure which blood test to book?
Book a free 15-minute video call with one of our Health Advisors. We talk through your symptoms or goals, recommend the right test and book it for you. No charge, no obligation.
Not near Sutton Coldfield? We offer blood tests across the UK through our partner network. This call is how a partner clinic appointment is booked: we complete the paperwork and arrange it for you, anywhere in the UK and Ireland.
Book a free discovery call or call 0121 387 3705