From the Guidelines
Radioiodine therapy is contraindicated in patients with thyroid eye disease (TED) due to the increased risk of exacerbating ocular symptoms. The use of radioactive iodine (I-131) treatment for hyperthyroidism can trigger or worsen TED in susceptible individuals, particularly those with pre-existing eye involvement, as it causes the release of thyroid antigens, intensifying the autoimmune response that affects orbital tissues 1. This is supported by a recent study published in 2024, which highlights that radioactive iodine treatment is an independent risk factor associated with the development of TED, along with other factors such as smoking, high anti-thyroid antibody titer, and serum vitamin D deficiency 1.
The risks associated with radioiodine therapy in patients with TED include increased orbital pressure, proptosis, diplopia, and even vision loss in severe cases. Alternative options for treating hyperthyroidism in patients with active TED include antithyroid medications like methimazole or propylthiouracil, or thyroid surgery. If radioiodine must be used in patients with mild TED, concurrent oral prednisone prophylaxis can reduce the risk of eye disease progression. However, it is essential to prioritize caution and consider the potential consequences of radioiodine therapy on TED, as emphasized by the most recent and highest quality study available 1.
Key considerations for managing TED in the context of hyperthyroidism treatment include:
- Avoiding radioiodine therapy whenever possible due to its potential to exacerbate TED
- Using alternative treatments such as antithyroid medications or thyroid surgery
- Implementing concurrent oral prednisone prophylaxis if radioiodine therapy is necessary
- Monitoring patients closely for signs of TED progression or worsening ocular symptoms.
From the Research
Contraindications for Radioiodine Therapy
- The use of radioiodine is contraindicated in certain conditions, including pregnancy and lactation 2, 3, 4.
- Relative contraindications include thyroid nodules suspected of malignancy and age under 15 years 2.
- In patients with thyroid-associated orbitopathy, radioiodine treatment may increase the inflammatory process and exacerbate the ophthalmological symptoms 2, 3.
Thyroid-Associated Orbitopathy
- Thyroid-associated orbitopathy cannot be considered as a contraindication for isotope therapy 2.
- However, patients with thyroid-associated ophthalmopathy should be followed up closely after I-131 therapy to rule out aggravation of their eye disease 3.
- The use of radioiodine in patients with thyroid eye disease is not explicitly contraindicated, but caution is advised due to the potential for exacerbating ophthalmological symptoms 2, 3, 4.
Radioiodine Therapy in Graves' Disease
- Radioiodine therapy is a common treatment for Graves' disease, with indications including recurrent hyperthyroidism after thyrostatic treatment or thyroidectomy, and side-effects observed during thyrostatic treatment 2.
- The therapy is based on short-range beta radiation emitted from radioactive iodine, and radioiodine administration must always be preceded by pharmacological normalization of thyroid function 2.