FT3 (Free Triiodothyronine) Test – Normal Range, Function, and Causes of High & Low Levels
The FT3 (Free Triiodothyronine) test measures the active thyroid hormone in your blood. It helps diagnose thyroid disorders such as hyperthyroidism or hypothyroidism. Learn about normal ranges, causes, and symptoms of high or low FT3 levels and how it reflects your thyroid health.



