Which statement best describes the thyroid function pattern seen in Graves’ disease?

Which statement best describes the thyroid function pattern seen in Graves’ disease?

• A. Suppressed TSH with elevated free T4
• B. Elevated TSH with elevated free T4
• C. Suppressed TSH with elevated free T4 and often elevated free T3
• D. Normal TSH with normal thyroid hormones

Answer: (C)

Graves disease causes the thyroid to be overactive because autoantibodies stimulate the TSH receptor, driving increased production and release of thyroid hormones T4 and T3. As these hormones rise, the pituitary senses the excess and suppresses TSH through negative feedback. The result is a pattern of a low or suppressed TSH with high free T4, and often elevated free T3 as well. In many patients, T3 rises even more prominently than T4, a situation sometimes described as T3-predominant hyperthyroidism. This combination—low TSH with elevated free T4 (and often elevated free T3)—is typical of Graves disease and helps distinguish it from other thyroid disorders, such as hypothyroidism (high TSH, low T4) or euthyroid states (normal TSH and normal thyroid hormones).

Graves disease causes the thyroid to be overactive because autoantibodies stimulate the TSH receptor, driving increased production and release of thyroid hormones T4 and T3. As these hormones rise, the pituitary senses the excess and suppresses TSH through negative feedback. The result is a pattern of a low or suppressed TSH with high free T4, and often elevated free T3 as well. In many patients, T3 rises even more prominently than T4, a situation sometimes described as T3-predominant hyperthyroidism. This combination—low TSH with elevated free T4 (and often elevated free T3)—is typical of Graves disease and helps distinguish it from other thyroid disorders, such as hypothyroidism (high TSH, low T4) or euthyroid states (normal TSH and normal thyroid hormones).