Free T3 measures the unbound, active form of triiodothyronine, the most potent thyroid hormone. It helps evaluate thyroid function and diagnose thyroid disorders.
Category: Thyroid Panel
Also known as: free t3, ft3, triiodothyronine free, free triiodothyronine
Reference range: 2–4.4 pg/mL (Source: ABIM)
Standard unit: pg/mL
High values may indicate
High free T3 may indicate hyperthyroidism, Graves' disease, T3 thyrotoxicosis, or early-stage thyroid overactivity.
Low values may indicate
Low free T3 may indicate hypothyroidism, severe non-thyroidal illness (sick euthyroid syndrome), or malnutrition.