FT3

About This Test
FT3 (Free Triiodothyronine) measures the active thyroid hormone circulating in blood, which drives metabolism, energy use, and heart rate. It helps evaluate thyroid overactivity (hyperthyroidism) and is interpreted together with TSH and FT4 to pinpoint thyroid imbalance and guide treatment.

Patient Preparation
Fasting not required.

Best Time to Test
Anytime

Tests Included
FT3

Why is it done
Symptoms such as tiredness, weight change, hair loss, or palpitations.
Investigating thyroid enlargement or nodules.
Routine screening in pregnancy or autoimmune disease.
Monitoring thyroid treatment.