Should thyroid nodules be monitored in a patient with a negative fine-needle aspiration (FNA) biopsy who undergoes Radioactive Iodine (RAI) treatment for Graves' disease?

From the Guidelines

Yes, thyroid nodules should still be monitored in someone with a negative thyroid nodule biopsy who undergoes radioactive iodine (RAI) treatment for Graves' disease. Follow-up ultrasound evaluations are typically recommended at 6-12 month intervals initially, then annually if the nodules remain stable, as suggested by the American College of Radiology guidelines 1. This monitoring is important because RAI treatment does not eliminate the small risk that benign nodules could change over time, and some nodules may not respond to RAI therapy. Additionally, RAI treatment itself can cause changes in thyroid tissue that should be monitored, as noted in the ESMO clinical practice guidelines for diagnosis, treatment, and follow-up of thyroid cancer 1. The frequency and duration of monitoring may be adjusted based on individual risk factors such as nodule size (nodules >1 cm warrant closer attention), growth pattern, and initial ultrasound characteristics. If significant growth (increase of >20% in at least two dimensions with a minimum increase of 2 mm) or suspicious ultrasound changes develop during follow-up, a repeat biopsy may be necessary despite the initial benign result, as recommended in the active surveillance strategy for low-risk papillary microcarcinoma 1. This ongoing surveillance provides reassurance while ensuring that any concerning changes are detected early. Key considerations in the management of thyroid nodules include the risk of overdiagnosis and overtreatment, as well as the importance of individualized care and patient education, as emphasized in the guidelines and studies cited above 1.

From the Research

Thyroid Nodule Monitoring after RAI Treatment for Graves' Disease

• The decision to monitor thyroid nodules in a patient with a negative thyroid nodule biopsy who undergoes RAI treatment for Graves' disease should be based on the individual's specific clinical history and characteristics.
• A study from 1996 2 found that RAI treatment can cause cytologic changes in the thyroid gland, which may lead to false positive diagnoses of malignancy.
• Another study from 2016 3 described the typical sonographic features of the thyroid gland after RAI therapy in patients with Graves' disease, including reduced volume, hypovascularity, coarse echotexture, and hyperechogenicity.
• However, there is no direct evidence to suggest that thyroid nodules should not be monitored in patients with a negative biopsy who undergo RAI treatment.
• In fact, a study from 2015 4 highlighted the importance of preoperative thyroid ultrasound in selecting patients with pediatric Graves' disease for definitive therapy, including those with concurrent differentiated thyroid cancer.

Considerations for Thyroid Nodule Monitoring

• The potential for RAI treatment to cause cytologic changes and false positive diagnoses should be taken into account when interpreting biopsy results 2.
• The sonographic features of the thyroid gland after RAI therapy should be considered when evaluating thyroid nodules 3.
• The presence of thyroid nodules and the results of fine needle aspiration biopsy should be carefully evaluated in patients with Graves' disease who undergo RAI treatment 4.
• The clinical history and characteristics of the individual patient should guide the decision to monitor thyroid nodules after RAI treatment.

RAI Treatment and Thyroid Function

• RAI treatment can cause transient or permanent hypothyroidism 5.
• The treatment aims to eliminate the functioning thyroid parenchyma using radiation, which can lead to DNA damage and cellular death 6.
• The effects of RAI treatment on thyroid function and the potential for thyroid nodules to develop or change after treatment should be considered when deciding whether to monitor thyroid nodules.