內分泌科題庫下載題庫

(2)

(3) 放射碘本身就是 Grave’s disease 的治療方式之一(P.2296)

The hyperthyroidism of Graves’ disease is treated by reducing thyroid hormone synthesis, using antithyroid drugs, or reducing the amount of thyroid tissue with radioiodine (131I) treatment or by thyroidectomy. Antithyroid drugs are the predominant therapy in many centers in Europe and Japan, whereas radioiodine is more

often the first line of treatment in North America.

The main antithyroid drugs are the thionamides, such as propylthiouracil, carbimazole (not available in the United States), and the active metabolite of the latter, methimazole. All inhibit the function of TPO, reducing oxidation and organification of iodide. These drugs also reduce thyroid antibody levels by mechanisms that remain unclear, and they appear to

enhance rates of remission. Propylthiouracil inhibits deiodination of T4 → T3.

(4) (5) P.2297

The titration regimen of antithyroid drugs should be used to manage Graves’ disease in

pregnancy because transplacental passage of these drugs may produce fetal hypothyroidism and goiter if the maternal dose is excessive. If available, propylthiouracil

should be used in early gestation because of the association of rare cases of fetal aplasia cutis and other defects, such as choanal atresia with carbimazole and methimazole. As noted above, because of its rare association with hepatotoxicity, propylthiouracil should be limited to the first trimester and then maternal therapy should be converted to methimazole (or carbimazole) at a ratio of 15–20 mg of propylthiouracil to 1 mg of methimazole The lowest effective antithyroid drug dose should be used throughout gestation to maintain the

maternal serum free T4 level at the upper limit of the nonpregnant normal reference range.

It is often possible to stop treatment in the last trimester because TSIs tend to decline in

pregnancy.