Is a patient with a mildly elevated 24‑hour thyroid radioiodine uptake of 33.7 %, no hyperfunctioning or hypofunctioning nodules, and no thyroid eye disease appropriate for radioactive iodine ablation therapy for Graves disease?

Radioactive Iodine Ablation for Graves' Disease with Mildly Elevated Uptake

Yes, this patient is appropriate for radioactive iodine ablation therapy for Graves' disease, as the 24-hour thyroid uptake of 33.7% confirms autonomous thyroid function consistent with Graves' disease, and the absence of thyroid eye disease removes a key relative contraindication that would otherwise require corticosteroid prophylaxis. 1, 2

Diagnostic Confirmation

Your patient's clinical picture supports Graves' disease as the diagnosis:

• A 24-hour radioiodine uptake of 33.7% is elevated (normal range is typically 10-30%), confirming hyperthyroidism with increased iodine avidity rather than destructive thyroiditis 1
• The absence of hyperfunctioning or hypofunctioning nodules on the uptake scan distinguishes Graves' disease from toxic multinodular goiter or toxic adenoma, both of which would show focal areas of increased uptake 1, 3
• The diffuse uptake pattern is characteristic of Graves' disease, where TSH-receptor antibodies stimulate the entire gland uniformly 2

Appropriateness of Radioactive Iodine Therapy

Radioactive iodine is highly appropriate and effective for this patient based on multiple considerations:

Efficacy and Safety Profile

• RAI eradicates hyperthyroidism in >90% of cases after a single dose, making it the most definitive non-surgical option 4
• RAI therapy is associated with the lowest morbidity and mortality among all available treatments for Graves' disease (compared to antithyroid drugs or surgery) 5
• Recent evidence demonstrates that RAI does not increase all-cause mortality, cardiovascular mortality, or cancer risk—in fact, it may reduce these risks when treatment promptly results in hypothyroidism 4

Absence of Thyroid Eye Disease

The absence of thyroid eye disease (TED) in your patient is a significant favorable factor:

• RAI carries a small risk (approximately 3.7%) of de novo occurrence or progression of mild Graves' ophthalmopathy, particularly in patients who develop early and prolonged hypothyroidism after treatment 2
• This risk is preventable with corticosteroid prophylaxis, but since your patient has no TED, this concern is minimized 2
• Patients who develop GO after RAI typically have high pretreatment TSH-receptor antibodies (TRAb) and antithyroid drug intolerance—monitor for these risk factors 2

Treatment Planning Considerations

Pre-Treatment Management

• If the patient is currently on methimazole, discontinue it 8 days before RAI administration to maximize treatment efficacy 6
• Continuous use of methimazole through RAI therapy reduces the cure rate (44% vs. 61% when stopped beforehand) by lowering the 24-hour thyroid uptake and interfering with radiation-induced cellular damage 6

Post-Treatment Monitoring

• Expect permanent hypothyroidism within months after ablative RAI doses—this is the intended outcome and should be managed with levothyroxine replacement 5, 4
• Early introduction of levothyroxine after RAI is recommended to reduce the duration and degree of radioiodine-induced hypothyroidism, which may lower the risk of developing ophthalmopathy 2
• TSH-receptor antibodies (TRAb) regress over time after successful RAI therapy, with 48.1% of patients achieving normalization 2

Common Pitfalls to Avoid

• Do not attempt levothyroxine suppression therapy in this patient—in Graves' disease with autonomous function, TSH is already suppressed, and definitive treatment (RAI or surgery) is required rather than medical suppression 3
• Avoid iodinated contrast agents before RAI treatment, as they competitively inhibit iodine uptake and diminish therapeutic efficacy 3
• Do not delay definitive therapy, especially in elderly patients, as postponing treatment increases the risk of serious cardiac complications, particularly atrial fibrillation 3
• Ensure the patient is not pregnant or breastfeeding, as these are absolute contraindications to RAI therapy 7

Alternative Considerations

Surgery (total or near-total thyroidectomy) would be preferred over RAI only if:

• The patient has a large goiter causing compressive symptoms (dyspnea, dysphagia, dysphonia) 3
• There are nodules suspicious for malignancy requiring histologic evaluation 3
• The patient is young with a long life expectancy and prefers to avoid lifelong hypothyroidism 3
• The patient is planning pregnancy in the near future (RAI requires 6-12 months delay) 4

Since your patient has none of these features and no TED, RAI ablation is the optimal first-line definitive therapy.