A 61-Year-Old Woman with Hyperthyroidism Is Treated with Propylthiouracil $\left(\mathrm{T}_{3}\right)$ B) Thyroxine

Multiple Choice

A 61-year-old woman with hyperthyroidism is treated with propylthiouracil. The drug reduces the synthesis of thyroid hormones because it inhibits oxidation of

A) Triiodothyronine $\left(\mathrm{T}_{3}\right)$
B) Thyroxine $\left(\mathrm{T}_{4}\right)$
C) Diiodotyrosine (DIT)
D) Thyroid-stimulating hormone (TSH)
E) Iodide ( $\mathrm{I}^{-}$ )