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Free T3 and Total T3

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Also known as: FT3; Triiodothyronine
Formal name: Free Triiodothyronine; Total Triiodothyronine

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At a Glance

Why Get Tested?

To help evaluate thyroid gland function; to diagnose thyroid disease, including hyperthyroidism, and determine the cause; to monitor effectiveness of treatment of a thyroid disorder

When to Get Tested?

When you have an abnormal TSH, particularly with a normal free T4 result, and/or signs and symptoms of hyperthyroidism

Sample Required?

A blood sample taken from a vein in your arm

Test Preparation Needed?

None needed; however, certain medications can interfere with the free T3 and total T3 tests, so tell your health practitioner about any drugs that you are taking.