What is Free Triiodothyronine (Free T3)?
Free Triiodothyronine is measured as part of a thyroid panel. Your Free T3 is in a healthy range — your thyroid is producing an appropriate amount of active hormone.
What does a high Free Triiodothyronine mean?
Your Free T3 is elevated, which can point to an overactive thyroid (hyperthyroidism) — symptoms include palpitations, weight loss, and anxiety. Worth discussing with your doctor.
What does a low Free Triiodothyronine mean?
Your Free T3 is low. T3 is the active thyroid hormone; a low level often goes alongside an underactive thyroid (hypothyroidism) and can cause tiredness, weight gain, and feeling cold.
Understand your whole report, not just one number
A single value rarely tells the full story — Free Triiodothyronine is best read alongside the rest of your panel. Paste your values or upload your report and get a plain-English explanation of every marker, with the important results flagged.