From the Guidelines
An autonomously functioning thyroid nodule is a growth in the thyroid gland that produces thyroid hormones independently of normal regulatory mechanisms, and it is crucial to prioritize treatment based on the most recent and highest quality study to minimize morbidity, mortality, and improve quality of life. These nodules, also called "hot nodules," make thyroid hormones without responding to thyroid-stimulating hormone (TSH) from the pituitary gland, which typically controls thyroid hormone production 1. They can cause hyperthyroidism when they produce excessive amounts of thyroid hormones. Autonomously functioning nodules are usually benign and account for about 5-10% of all thyroid nodules. They develop due to genetic mutations affecting thyroid cell growth and function, particularly mutations in the TSH receptor or G-protein genes. Some key points to consider include:
- Diagnosis typically involves blood tests to measure thyroid hormone levels and TSH, along with thyroid imaging such as radioactive iodine or technetium scans, which show these nodules as areas of increased uptake (appearing "hot" on the scan) while the rest of the gland shows reduced activity 1.
- Treatment options include radioactive iodine therapy to destroy the overactive tissue, surgery to remove the nodule, or medications like methimazole or propylthiouracil to control hyperthyroid symptoms until definitive treatment 1.
- The USPSTF found no direct evidence that treatment of thyroid dysfunction based on risk level alters final health outcomes, emphasizing the need for careful consideration of treatment approaches 1.
- Common causes of hyperthyroidism include Graves disease, Hashimoto thyroiditis, and functional thyroid nodules, with risk factors for a low TSH level including female sex, advancing age, and personal or family history of thyroid disease 1.
- The principal treatment for hypothyroidism is oral T4 monotherapy (levothyroxine sodium), while hyperthyroidism is treated with antithyroid medications or nonreversible thyroid ablation therapy 1. In summary, the management of autonomously functioning thyroid nodules requires a comprehensive approach, taking into account the latest evidence and individual patient factors to optimize outcomes and minimize risks.
From the Research
Definition and Characteristics of Autonomously Functioning Thyroid Nodules
- Autonomously functioning thyroid nodules (AFTNs) are thyroid nodules that function independently of TSH for growth and function 2.
- They appear "hot" on scintiscan because they selectively concentrate radionuclide to a greater extent than the remaining thyroid gland 2.
- AFTNs may occur as solitary nodules or as multiple nodules, and their mass and related secretion of thyroid hormones determine whether the patient is euthyroid or hyperthyroid 2.
Diagnostic Tests and Treatment Options
- Important diagnostic tests for AFTNs include 99mTc thyroid scan, T4 RIA, T3 uptake, FTI, TSH RIA, and occasionally T3 RIA 2.
- Treatment options for AFTNs include surgery, radioactive iodine, and novel approaches such as radiofrequency ablation (RFA) and transoral endoscopic thyroid surgery 3, 4, 5.
- RFA has been shown to be a safe and effective treatment option for AFTNs, with a high success rate in resolving hyperthyroidism and reducing nodule volume 4, 5.
Patient-Specific Treatment Considerations
- The decision to treat a solitary nodule depends on the size and degree of function of the nodule, as well as the patient's age 2.
- Surgery is often recommended for patients with large nodules or those who are young, while radioactive iodine may be preferred for older patients or those with smaller nodules 2, 6.
- RFA may be considered an alternative treatment option for patients who are high-risk surgical candidates or have contraindications to radioactive iodine 5.