Triiodothyronine (T3) as compared to T4:
High-Yield Explanation
(Ref: KDT 6/e p247) T3 is the main active thyroid hormone. It is more potent (less plasma protein bound) and faster acting than T4. However, sho duration of action limits its use for the treatment of hypothyroidism (requires life long treatment). T3 is indicated for the treatment of myxedema coma.