What is a thyroid nodule?
A thyroid nodule is a lump or growth that develops in your thyroid gland. The thyroid is a small, butterfly-shaped gland located at the base of your neck. It’s job is to produce hormones that regulate your metabolism. A thyroid nodule is a benign (non-cancerous) or malignant (cancerous) growth in the thyroid.
Thyroid nodules are very common, especially as people age. An estimated 50-60% of people will develop a thyroid nodule during their lifetime. However, only about 5% of all thyroid nodules are cancerous.
What causes thyroid nodules?
There are several potential causes of thyroid nodules:
– Iodine deficiency – Consuming too little iodine can cause the thyroid to become enlarged and develop nodules. Iodine is essential for proper thyroid hormone production.
– Hashimoto’s thyroiditis – This autoimmune disorder causes inflammation of the thyroid gland, which can lead to nodules forming.
– Genetic mutations – Inherited genetic changes can make the thyroid prone to developing nodules and other abnormalities.
– Prior radiation exposure – Radiation exposure to the thyroid during medical imaging or treatment can increase the risk of nodules.
– Age – Thyroid nodules become more common as people age. The reasons are unclear.
– Being female – Women are 2-3 times more likely to develop thyroid nodules compared to men. Female sex hormones may play a role.
– Pregnancy – Hormonal changes during pregnancy can cause nodule growth. Most regress after giving birth.
Signs and symptoms of a thyroid nodule
Most thyroid nodules do not cause any symptoms. They are often found incidentally during a routine medical exam when the doctor feels a lump in the neck. Symptoms that can occasionally occur with a thyroid nodule include:
– A neck lump that can be felt by touch – This is the classic symptom. However, most nodules found are too small to be felt.
– Trouble swallowing or breathing – If a nodule grows large enough, it can press on the esophagus or windpipe.
– Hoarse voice or cough – A large nodule may compress the recurrent laryngeal nerve, causing vocal changes.
– Hyperthyroidism symptoms – Excessive thyroid hormone production, causing sudden weight loss, rapid heartbeat, etc. This is more common with toxic nodules.
– Hypothyroidism symptoms – Fatigue, weight gain, hair loss, etc. from too little thyroid hormone. This can occur if a nodule disrupts overall gland function.
If you have any suspicious neck lumps or unexplained thyroid symptoms, see your doctor. An evaluation is needed to determine the cause and if any treatment is required.
Are thyroid nodules dangerous?
The vast majority of thyroid nodules are benign growths that do not pose any health risks. However, there are some situations in which thyroid nodules can be dangerous:
– Cancer risk – About 5-15% of nodules harbor thyroid cancer. This is more likely in large nodules over 2 cm.
– Compression symptoms – Very large nodules can sometimes cause breathing issues or trouble swallowing if they press on vital neck structures.
– Hyperthyroidism – Autonomous nodules that overproduce thyroid hormone can trigger the effects of hyperthyroidism like rapid heart rate.
– Cosmetic concerns – Some people want nodules surgically removed for cosmetic reasons if large enough to be visible as a neck bulge.
So while most nodules are harmless, it’s important to have all nodules evaluated for the above concerns. Ultrasound and biopsy are often needed to rule out cancer and determine appropriate treatment.
Risk factors for thyroid cancer in a nodule
While most thyroid nodules are benign, here are some factors that raise suspicion for cancer:
– Older age – Risk increases steadily after age 25-30.
– Male sex – Men have a higher cancer risk in nodules than women.
– Family history – Having a first-degree relative with thyroid cancer.
– Radiation exposure – Particularly in childhood or young adulthood.
– Rapid nodule growth – Faster enlargement raises suspicion.
– Firm, hard nodules – Cancerous nodules are often solid and firm.
– Hoarse voice – Can signal recurrent laryngeal nerve invasion.
– Swollen lymph nodes – Might indicate thyroid cancer spread.
– Nodule size – Over 4 cm diameter or 2 cm high risk features.
– Hyperthyroidism – Toxic nodules have a 10-20% cancer prevalence.
If your nodule has any of these red flags, cancer evaluation and monitoring are important.
Tests and diagnosis of thyroid nodules
If a thyroid nodule is found, your doctor will likely order the following tests to evaluate it:
– Medical history – Personal and family history of thyroid disorders or cancer.
– Physical exam – Feeling the neck to characterize nodule size, consistency, and mobility.
– Ultrasound – Uses soundwaves to create an image showing nodule appearance, composition, and blood flow.
– Thyroid lab tests – Measuring TSH and thyroid hormone levels to assess gland function.
– Radioactive iodine scan – Swallowed iodine will be taken up more by functional nodules than normal tissue.
– Fine needle aspiration biopsy – Using a needle to extract cells from the nodule for examination under a microscope. This is the definitive way to identify cancer.
These tests help classify nodules as benign or suspicious. They also guide what type of follow-up monitoring or treatment will be needed.
Typical thyroid nodule evaluation and diagnosis
| Test | Purpose |
|---|---|
| Medical history and physical exam | Assess background risk factors and feel for lumps or enlarged lymph nodes |
| Thyroid ultrasound | Evaluate nodule size, appearance, and characteristics |
| Thyroid lab tests (TSH, T3, T4) | Determine if nodule is impacting hormone production |
| Radioactive iodine scan | See if nodule is “hot” or “cold” – functional vs non-functional |
| Fine needle aspiration biopsy | Extract cells to examine under microscope for cancer signs |
Benign thyroid nodule treatment
If testing confirms a thyroid nodule is benign, common treatment approaches include:
– Observation – No treatment beyond regular ultrasound monitoring to watch for growth. This is often done for small asymptomatic nodules under 2cm with benign appearance.
– Levothyroxine therapy – Taking supplemental thyroid hormone can help shrink benign nodules in some cases. It works by suppressing TSH production.
– Radioactive iodine – Swallowing a radioactive iodine dose can shrink and destroy benign overactive nodules that make too much thyroid hormone. It is a non-surgical alternative.
– Surgery – Removal of part or all of the thyroid gland if nodules are large, causing symptoms, or patient desires it. The most common surgery is a thyroid lobectomy to remove the side with the nodule.
– Ethanol ablation – Injecting sterile alcohol into the nodule kills thyroid cells, shrinking the nodule’s size over time. This is a less invasive option.
– Laser ablation – Using laser heat to destroy thyroid cells and shrink the nodule without surgery.
The best approach depends on the nodule’s specific characteristics. Your endocrinologist will guide you through the options.
Thyroid cancer nodule treatment
If a nodule biopsy confirms thyroid cancer, common treatment options include:
Surgery
– Thyroidectomy – Removal of the entire thyroid gland plus nearby lymph nodes. This is typically the initial treatment for most thyroid cancers.
– Lobectomy – Removing only the side of the thyroid with cancer. This may be adequate for small papillary thyroid cancers.
Radioactive iodine ablation
– Swallowing a radioactive iodine isotope locates and destroys any remaining thyroid tissue. It helps eliminate residual cancer cells.
Thyroid hormone therapy
– Levothyroxine pills are given to replace missing thyroid hormone after surgery. This also helps suppress cancer recurrence.
External beam radiation therapy
– A concentrated beam of radiation to the neck and thyroid bed. This can help eliminate any lingering cancer.
The combination of surgery, radioactive iodine, and thyroid hormone is effective for most thyroid cancers. Chemotherapy is occasionally used for more advanced cancers.
What is the prognosis for thyroid cancer?
Most thyroid cancers have an excellent prognosis, especially when found early:
– Papillary thyroid cancer – Over 95% 10-year survival rate. Most curable thyroid cancer.
– Follicular thyroid cancer – 90% 10-year survival rate with timely treatment.
– Medullary thyroid cancer – 85% 10-year survival rate if localized tumor removed.
– Anaplastic thyroid cancer – 20% 5-year survival rate. Most aggressive type.
Key factors that affect prognosis include patient age, tumor stage, and cell type. Overall, thyroid cancer is one of the most curable cancers when managed appropriately. Lifelong thyroid hormone therapy and monitoring are still required after successful treatment.
Can a benign thyroid nodule turn cancerous later?
It is uncommon for a truly benign thyroid nodule to suddenly turn cancerous and malignant. However, there are a few scenarios in which this can occasionally happen:
– Inadequate biopsy – A nodule initially thought benign may actually have been a well-differentiated thyroid cancer that was misdiagnosed on biopsy. Repeat biopsy may read it accurately as cancerous.
– New nodule growth – A brand new nodule can arise in the thyroid separate from the original benign nodule and this new one could be malignant.
– Partial malignant transformation – In rare cases, a portion of cells within a benign nodule may transform and take on cancerous characteristics while the rest remain benign.
For these reasons, it is important to monitor any benign nodules with repeat ultrasounds over time. Size changes, new growths, or suspicious alterations should prompt re-evaluation and repeat biopsy if appropriate.
Takeaway points on thyroid nodules:
– Thyroid nodules are extremely common, occurring in over half of people.
– Approximately 5% of nodules will be cancerous, but most are benign.
– Have all new nodules evaluated with ultrasound, lab tests, and possibly biopsy.
– Benign nodules may simply be monitored or treated with thyroid hormones, radioactive iodine, or surgery.
– Cancerous nodules require surgery and often radioactive iodine and long term thyroid hormone therapy.
– Thyroid cancers found early have a good prognosis with proper treatment.
– Very rarely, cancer can develop in a nodule previously thought to be benign. Ongoing monitoring is important.
See your doctor promptly if you notice a neck lump or thyroid nodule. Early evaluation and management are key to achieving the best outcome. Most nodules will be benign, but it’s always wise to rule out the possibility of cancer.
