The total triiodothyronine (T3) test is one of several tests used to diagnose thyroid disorders. T3 is an active thyroid hormone that your body creates by converting thyroxine (T4) into ...

Triiodothyronine, or T3, is an important thyroid hormone that helps maintain muscle control, brain function and development, heart and digestive functions. High or low T3 levels may indicate an ...

Medically reviewed by Isabel Casimiro, MD, PhD A TSH test measures the level of thyroid-stimulating hormone in your blood. Abnormal TSH levels typically indicate a problem with your thyroid, like ...