Which autoantibody binds to TSH receptor sites on thyroid cell membranes and prevents TSH from binding?

Which autoantibody binds to TSH receptor sites on thyroid cell membranes and prevents TSH from binding?

• A. Antithyroglobulin antibodies
• B. Thyroid antimicrosomal antibodies
• C. Thyrotropin-receptor antibodies
• D. Antithyroid peroxidase antibodies

Answer: (C)

Binding to the TSH receptor on thyroid cells and blocking TSH from attaching is a function of thyrotropin-receptor antibodies. These antibodies dock at the receptor site, preventing the hormone TSH from binding and triggering the signaling that would normally boost thyroid hormone production. This receptor-targeting antibody can act in different ways, but the key point for this question is that it interferes with TSH binding by occupying the receptor. The other antibodies listed target other thyroid components (like thyroglobulin or thyroid peroxidase) and do not directly block the TSH receptor, so they don’t prevent TSH from binding.

Binding to the TSH receptor on thyroid cells and blocking TSH from attaching is a function of thyrotropin-receptor antibodies. These antibodies dock at the receptor site, preventing the hormone TSH from binding and triggering the signaling that would normally boost thyroid hormone production. This receptor-targeting antibody can act in different ways, but the key point for this question is that it interferes with TSH binding by occupying the receptor. The other antibodies listed target other thyroid components (like thyroglobulin or thyroid peroxidase) and do not directly block the TSH receptor, so they don’t prevent TSH from binding.