A nurse suspects a patient taking propylthiouracil may have which condition?

The patient taking propylthiouracil may have Graves' disease because this medication is commonly used to manage hyperthyroidism, which is often caused by Graves' disease. Graves' disease is an autoimmune disorder characterized by overactivity of the thyroid gland, leading to an excess production of thyroid hormones. Propylthiouracil helps to decrease the production of these hormones by inhibiting the enzyme necessary for their synthesis.

In contrast, myxedema is a severe form of hypothyroidism, Addison's disease relates to adrenal insufficiency, and Cushing's syndrome is associated with excess cortisol production. Therefore, the context in which propylthiouracil is prescribed aligns specifically with the treatment of Graves' disease.