The question is incomplete. The complete question is:
"In Graves disease, thyroid-stimulating immunoglobulins (TSI) contain an active site that can mimic the active site of TSH to stimulate thyroid hormone production. One would expect TSI to cause:"
A. An increase in thyroid gland size because of the trophic effect of TSH.
B. A decrease in thyroid gland size because of competitive inhibition with TSH.
C. No change in thyroid gland size because antibodies only recognize foreign particles.
D. An immune response against TSH molecules.
Answer:
A. An increase in thyroid gland size because of the trophic effect of TSH.
Explanation:
Thyroid-stimulating hormone is a trophic hormone and is released by the anterior pituitary gland. It targets the thyroid gland and stimulates it to release the thyroid hormones. Graves disease is an autoimmune disorder in which the person produces antibodies such as thyroid-stimulating immunoglobulins that mimic the action of thyroid-stimulating hormone (TSH).
These antibodies continually stimulate the thyroid gland to grow and produce thyroid hormones. The result is an abnormally enlarged thyroid gland. The affected individuals also develop peculiar edema behind the eyes that causes the eyes to protrude.
