Thyroid nodules are common growths of cells that form a lump within the thyroid gland in the lower front of the neck. These nodules are often discovered incidentally during routine physical exams or imaging. While the presence of a lump can be concerning, the vast majority of thyroid nodules, over 90%, are benign (noncancerous). While most are harmless, a small percentage can be cancerous, requiring careful evaluation.
Understanding Thyroid Nodule Evaluation
Evaluation of thyroid nodules determines their characteristics. It starts with a physical examination to assess size and texture. Blood tests also check thyroid function, measuring thyroid-stimulating hormone (TSH) levels. While abnormal TSH can indicate a nodule that is producing excess hormones, most thyroid nodules, including those that are cancerous, do not affect TSH.
Thyroid ultrasound is a primary imaging tool used to characterize nodules in detail. It provides images revealing the nodule’s size, shape, borders, and internal features like calcifications (tiny calcium deposits) and vascularity (blood flow). Certain ultrasound characteristics, like irregular margins or microcalcifications, can raise suspicion for malignancy. Based on ultrasound findings and nodule size, a fine needle aspiration (FNA) biopsy may be recommended.
An FNA biopsy uses a thin needle to withdraw cells from the nodule, often with ultrasound guidance for accuracy. Multiple samples are taken to obtain diagnostic material. The collected cells are then examined by a pathologist, and the results are often categorized using the Bethesda System for Reporting Thyroid Cytopathology. This standardized system helps classify the likelihood of malignancy, ranging from benign to malignant, guiding management decisions.
Non-Surgical Management Approaches
For benign thyroid nodules or those with very low malignancy risk, non-surgical management is often preferred. Active surveillance involves regular follow-up appointments and repeat thyroid ultrasounds, typically every 6 to 12 months. This allows healthcare providers to monitor the nodule for any changes in size or suspicious features over time, ensuring early detection of any concerning developments.
Thyroid hormone suppression therapy, using medication like levothyroxine, may be considered for certain benign nodules (e.g., colloid nodules or multinodular goiters). It suppresses TSH levels, which can sometimes reduce the size of the nodule or prevent its growth by decreasing thyroid cell stimulation.
Minimally invasive procedures offer additional non-surgical options for benign symptomatic nodules, especially those causing compressive symptoms or cosmetic concerns. Radiofrequency ablation (RFA) uses heat to shrink the nodule, while ethanol ablation (PEI) involves injecting ethanol into the nodule to destroy its cells. These procedures are typically performed on an outpatient basis and are considered when a nodule is benign but causing discomfort like difficulty swallowing or a visible lump.
Surgical Removal for Thyroid Nodules
Surgical intervention becomes necessary for thyroid nodules in specific scenarios, particularly when malignancy is confirmed or highly suspected. Surgery is also considered for nodules with suspicious cytology results from an FNA biopsy, even if cancer is not definitively diagnosed. Large benign nodules that cause compressive symptoms, such as difficulty breathing, swallowing, or a persistent “tickle in the throat,” often warrant surgical removal to alleviate these issues. Cosmetic concerns due to a visibly prominent nodule can also be a reason for surgery.
Several types of thyroid surgery are performed, with the choice depending on the nodule’s characteristics and the extent of the disease. A lobectomy involves removing only the half of the thyroid gland that contains the nodule, often favored for smaller, solitary nodules or low-risk cancers. A total thyroidectomy, which is the removal of the entire thyroid gland, is typically recommended for larger cancers, multifocal disease, or when there is a high risk of recurrence.
The decision between these surgical approaches is influenced by factors such as the nodule’s size, the type and stage of cancer if present, and the patient’s overall health. Following a total thyroidectomy, patients will require lifelong thyroid hormone replacement therapy, as the body can no longer produce its own thyroid hormones. After a lobectomy, some patients may still need hormone replacement, depending on the remaining thyroid’s function.
Ongoing Monitoring and Follow-Up
Long-term care and monitoring are integral parts of managing thyroid nodules, regardless of whether the initial approach was surgical or non-surgical. Regular follow-up appointments with a healthcare provider are important to assess overall health and discuss any new symptoms. Continued imaging, primarily with thyroid ultrasound, is generally recommended to check for any changes in existing nodules or the appearance of new ones.
Blood tests are also a routine part of ongoing surveillance. For all patients, TSH levels are periodically checked to ensure proper thyroid function. In cases where a total thyroidectomy was performed for cancer, thyroglobulin levels are monitored as a tumor marker to detect any potential recurrence of thyroid cancer. Adherence to prescribed medication, such as thyroid hormone replacement therapy, is important for maintaining well-being, especially after surgical removal of the thyroid gland.