Graves disease is best described as?

• A. Hyperthyroidism with thyroid-stimulating antibodies
• B. Hypothyroidism with anti-TPO antibodies
• C. Hyperthyroidism with TSH receptor antibodies
• D. Normal thyroid function

Answer: (C)

Graves disease is an autoimmune hyperthyroidism caused by antibodies that stimulate the TSH receptor on thyroid follicular cells. These TSH receptor–stimulating antibodies (often called TSH receptor antibodies) bind the receptor and mimic TSH, driving increased production and release of thyroid hormones T3 and T4. The result is a hyperthyroid state with suppression of TSH due to negative feedback. The presence of anti-TPO antibodies is more typical of Hashimoto thyroiditis, which leads to hypothyroidism, not Graves. Normal thyroid function would not reflect Graves disease. So the description that best fits Graves is hyperthyroidism driven by TSH receptor antibodies.