Final answer:
Methimazole is the first-line treatment for Graves' disease. It inhibits the synthesis of thyroid hormones by preventing the thyroid gland from using iodine. Propylthiouracil is an alternative, and Radioactive iodine or Levothyroxine are not first-line treatments for Graves' disease.
Step-by-step explanation:
First-line Treatment for Graves' Disease
The first-line treatment for Graves' disease, a common autoimmune disorder affecting the thyroid gland, is antithyroid drugs. The primary goal of these medications is to control hyperthyroidism by inhibiting the synthesis of thyroid hormones.
The specific antithyroid medications used include Methimazole (MMI) and Propylthiouracil (PTU), with Methimazole often being preferred due to its lower incidence of side effects.
Methimazole is a thyroperoxidase inhibitor, meaning it prevents the thyroid gland from using iodine to produce thyroid hormones, thus lowering hormone levels. While PTU plays a similar role, Methimazole is typically favored in the majority of cases except during the first trimester of pregnancy or in instances of Methimazole intolerance.
Another treatment option for Graves' disease is Radioactive iodine, which can serve as an ablation therapy to reduce thyroid tissue and function. However, it is not typically the first line but may be considered if antithyroid drugs are not successful or suitable. Additionally, Levothyroxine is not a treatment for hyperthyroidism; instead, it is used to treat hypothyroidism by supplementing low thyroid hormone levels.
In conclusion, the correct answer to the question of which medication is considered the first-line treatment for Graves' disease is Methimazole (Option A).