Review Question - QID 204423

This patient's Graves' ophthalmopathy was worsened by the initiation of radioactive iodine. Pretreatment with glucocorticoids, such as prednisone, may prevent this adverse effect.

Worsening of exophthalmos is due to the release of excess thyroid hormone during the destruction of thyroid cells by the radioactive iodine. Administration of radioactive iodine may also precipitate a thyroid storm through an identical mechanism. Preventive administration of steroids for several months (2-3) followed by a brief taper prior to initiating radioiodine therapy is recommended for patients with mild, moderate, or progressive ophthalmopathy. Patients without obvious ophthalmopathy initially are at a much lower risk of exacerbation with the start of radioactive iodine treatment.

Reid and Wheeler discuss the diagnosis and management of hyperthyroidism. In the US, radioiodine therapy is the first-choice treatment for hyperthyroidism and Graves' disease. Graves opthalmopathy may develop or worsen in 15% of patients who receive radioiodine therapy. Post-treatment hypothyroidism may be associated with worsening of ophthalmopathy; therefore, lower doses of radioiodine therapy may be considered.

Chen et al. investigate changes in Graves' ophthalmopathy after undergoing radioiodine or anti-thyroid treatment. They find that thyroid function is likely the most important factor in the worsening of Graves' ophthalmopathy regardless of treatment modality. Thus, they recommend striving for euthyroidism as a goal of treatment.

Illustration A shows a management algorithm for Graves' ophthalmopathy. Illustration B demonstrates the pathogenesis of Graves' ophthalmopathy; Graves' ophthalmopathy is due to an inflammatory autoimmune response that leads to deposition of glycosaminoglycans in the extraocular muscles and retroorbital connective tissues. There are numerous hypotheses as to the specific autoantibodies and targets responsible.

Incorrect Answers:
Answer 1: A larger dose of radioiodine could have led to an even greater exacerbation of the patient's exophthalmos. A smaller dose could have mitigated the effect of the radioiodine.
Answer 2: Beta-blockers act to control the symptoms of hyperthyroidism, notably tachycardia and palpitations; initiating a beta-blocker would not be expected to decrease the risk or severity of the worsening of this patient's ophthalmopathy.
Answer 3: Antithyroid drugs should be stopped prior to initiating therapy with radioactive iodine.
Answer 5: Pretreatment with glucocorticoids has been shown to decrease the risk or extent of worsening exophthalmos after initiating radioactive iodine therapy.