There are two different types of thyroid hormones, T3 and T4. These two types mostly differ in their concentrations and potencies, with T3 being approx. 3x more potent than T4, and T4 being approx. 4x more prevalent in the bloodstream. T4 is transformed into the more active version, T3. Both of these hormones play major roles in the development, growth, metabolism, and physiological function in virtually all tissues. Graves’ Disease is an autoimmune disease that causes the thyroid gland to overproduce T3 and T4. The most obvious symptoms of Graves’ Disease include protruding eyes and a swollen neck.