A 32-year-old woman comes to the physician because of a 3-month history of palpitations, weight loss, and heat intolerance. She also reports that her eyes feel "gritty" and have been appearing more prominent in the mirror. She has no significant past medical history and takes no medications. Vital signs include a heart rate of 106/min and a blood pressure of 130/82 mmHg. On physical examination, there is mild bilateral proptosis, conjunctival injection, and lid lag. The thyroid gland is diffusely enlarged, smooth, and nontender. A faint bruit is audible over the gland. Fine tremors are noted in the fingers when the arms are extended. Laboratory studies show a serum thyroid-stimulating hormone (TSH) level of <0.01 μU/mL (N = 0.5–5.0) and an elevated free thyroxine (T4) level. The patient expresses a preference for definitive treatment for her condition. Which of the following is the most appropriate next step to achieve her request?
The correct answer is:
D) Radioactive iodine with glucocorticoids
Radioactive iodine (RAI) is a first-line definitive treatment for Graves disease in the United States. However, RAI can exacerbate Graves ophthalmopathy because the destruction of the thyroid gland releases thyroid antigens, leading to an increase in TSH receptor antibody levels. In patients with mild ophthalmopathy who choose RAI, the administration of concurrent glucocorticoids (e.g., prednisone) is recommended to prevent this from occurring. This patient has mild proptosis and conjunctival injection, making RAI with glucocorticoid prophylaxis the most appropriate definitive management strategy.
Answer choice A: Methimazole, is incorrect. Methimazole is a thionamide used for the medical management of hyperthyroidism. While it is often used to achieve euthyroidism before definitive treatment or as long-term therapy, it is associated with a high rate of relapse (approximately 50%) after discontinuation and is generally not considered definitive treatment in the same way as RAI or surgery.
Answer choice B: Propylthiouracil, is incorrect. Propylthiouracil (PTU) is a thionamide that is typically reserved for the first trimester of pregnancy or the management of thyroid storm due to the risk of severe hepatotoxicity. Like methimazole, it is used for medical management and does not provide definitive treatment of the underlying hyperthyroidism.
Answer choice C: Radioactive iodine, is incorrect. Radioactive iodine ablation alone is a definitive treatment for Graves disease, but it is contraindicated as monotherapy in patients with pre-existing ophthalmopathy. Without glucocorticoid coverage, RAI can significantly worsen the patient's proptosis and orbital inflammation.
Answer choice E: Total thyroidectomy, is incorrect. Total thyroidectomy is a definitive treatment for Graves disease and is the preferred option for patients with severe ophthalmopathy, very large goiters, or suspected malignancy. However, for a patient with mild ophthalmopathy, RAI with glucocorticoid coverage is generally preferred as it is less invasive and avoids the risks associated with surgery, such as recurrent laryngeal nerve injury and hypoparathyroidism.
Key Learning Point
Radioactive iodine (RAI) therapy for Graves disease can lead to the worsening of ophthalmopathy due to an increase in TSH receptor antibody levels following glandular destruction. In patients with mild ophthalmopathy undergoing RAI therapy, glucocorticoids should be administered concurrently to prevent exacerbation. Total thyroidectomy is the preferred definitive treatment for patients with moderate-to-severe ophthalmopathy.
