Diagnosis & Treatment of Thyroid Nodules

If you discover a nodule or tumor in your neck are only a series of diagnostic tests can determine if it's benign or malignant (cancerous) and can help to guide treatment decisions. There are several diagnostic tests; each provides unique information about the nodule. It is important to know that tests are ordered based upon a patient's medical history, symptoms, and physical examination.

Often, a diagnostic test will provide a definitive answer about the type and cause of a nodule. In other cases, a test may be inconclusive and further testing will be required. Your doctor or nurse can discuss with you  the reason for each test and explain what the results mean.

Physical Examination

— Diagnosis may begin with questions about a patient's medical history and a physical examination. A clinician may be able to distinguish nodules by carefully palpating (feeling) the thyroid gland. However, some nodules are too small to be felt, and some lie in areas that cannot be felt during examination. Physical examination alone cannot determine if a nodule is benign or malignant or if it is producing excess thyroid hormone.

Certain features increase the likelihood that a nodule is malignant. These features include rapid growth of a large, solid nodule; a nodule that is hard and cannot be moved; symptoms suggesting that the esophagus or trachea is narrowed or obstructed; swelling of the lymph nodes in the neck or under the jaw; and hoarseness.

Among all people with thyroid nodules, several factors may also increase the likelihood that a thyroid nodule is malignant.

• Age — A thyroid nodule occurring in a child or in an adult under age 20 or over age 60 is more likely to be malignant.

• Gender — Thyroid cancer is found in 8 percent of men and only 4 percent of women who have thyroid nodules.

• Previous radiation treatment to the head or neck — In the past, radiation was used to treat acne, inflamed tonsils and adenoids, and an enlarged thymus gland. It was later recognized that radiation exposure increases a person's risk of thyroid nodules and thyroid cancer. A healthcare provider should closely monitor the thyroid gland in people who have had radiation treatment. Patients who have had radiation treatment to the head or neck should discuss this with their clinician.

Laboratory Testing:

Blood tests — Blood tests are routinely performed in the process of evaluating a thyroid nodule. These blood tests measure the levels of hormones and antibodies (proteins) in the blood.

• Thyroid stimulating hormone — Low levels of thyroid-stimulating hormone (TSH) may indicate that a nodule is producing high levels of thyroid hormone. High levels of TSH may indicate autoimmune inflammation of the thyroid (called Hashimoto's thyroiditis).

• Anti-thyroid peroxidase antibodies — The presence of anti-thyroid peroxidase antibodies may also indicate autoimmune inflammation of the thyroid gland.

• Calcitonin — High levels of calcitonin can indicate a specific type of thyroid cancer, called medullary thyroid cancer. However, high calcitonin levels can also be found in people who do not have this cancer. This test is typically reserved for patients with a family history of medullary cancer. However, some studies suggest that it should be ordered more often.

Radiology Testing

• Thyroid ultrasound — Thyroid ultrasound provides the best information about the shape and structure of the thyroid gland and thyroid nodules. It can identify very small nodules and can differentiate between solid and cystic (fluid-filled) nodules. Ultrasound can also identify features that are potentially suspicious for cancer. However, ultrasound does not provide information about the function of a nodule.

• Thyroid scan — A thyroid scan can help to determine if a nodule is autonomous ("hot") or non-functional ("cold"). The scan is performed after a patient is given a small dose of a radioactive substance (either iodine or technetium) by pill or injection. In a person with hyperthyroidism (low levels of thyroid stimulating hormone (TSH)), nodules that absorb the radioactive substance are usually not cancerous (called autonomous, hot, or toxic). Nodules that do not absorb the radioactive substance are called cold, and have a 5 percent risk of being cancerous. Approximately 95 percent of nodules are cold.

Sometimes the results of thyroid scan are indeterminate. In this case, the test may be repeated after treatment with synthetic thyroid hormone (T4). This approach can help to define a nodule's status.

The risk of exposure to radiation is small compared to the benefit of knowing the test's results. Women who are pregnant or breastfeeding should not have this test. Following a thyroid scan, patients should take care to flush the toilet and wash their hands after urinating; the radioactive substance is eliminated in the urine.

BIOPSY

• Fine Needle Biopsy -- Fine-needle aspiration biopsy is the most sensitive way of diagnosing the cause of a thyroid nodule. It uses a thin needle to remove small tissue samples from the nodule. These samples are examined with a microscope. Ultrasound is frequently used to guide the needle to smaller nodules. Aspiration can also be used to remove a sample of fluid from cystic (fluid-filled) nodules.

FNA biopsy can be performed in the office with a local anesthetic (numbing medicine). A patient usually feels mild discomfort as the anesthesia is injected, but will not feel pain during the biopsy.

This test is very accurate in identifying cancer in a suspicious nodule, although sometimes the results are indeterminate and surgery is necessary. Surgery can definitively determine if a nodule is benign or malignant.

The results of the biopsy can be one of the following:

• Benign (noncancerous)
• Malignant (cancer)
• Indeterminant or suspicious
• Nondiagnostic or insufficient

TREATMENT OF THYROID NODULES

The appropriate treatment for a thyroid nodule will depend upon the type of nodule.

• Benign nodules — These nodules usually develop as a result of overgrowth of normal components of the thyroid gland. Surgery is not usually recommended, and the nodule can usually be monitored over time. If the nodule grows, a repeat biopsy or surgery may be recommended.

• Suppressive (thyroid hormone) treatment — A clinician may suggest a trial of T4 in doses slightly higher than the thyroid normally produces; this is called suppressive treatment. If the nodule shrinks with treatment, it is more likely to be benign, although some malignant nodules will also respond. Thus, most experts do not recommend using this test to classify a nodule as benign or malignant.

• Malignant nodules (thyroid cancer) — Only about 5 percent of all thyroid nodules are malignant. The majority of thyroid cancers are papillary thyroid cancer. Most patients with thyroid cancer have an excellent chance for cure or long-term survival.

The treatment of thyroid cancer will depend on the type of cancer. Thyroid cancers require surgical removal of the thyroid gland and one or more treatments with radioiodine, followed by thyroid hormone (T4) suppressive therapy.

• Indeterminate or suspicious nodules — These nodules are not officially classified as malignant nodules, but they share many features with thyroid cancer. With time, they may invade surrounding tissues, at which point they are classified as cancer.

Surgical removal of these nodules is generally recommended. At the time of surgery, about 10 to 20 percent of suspicious nodules have become invasive and are classified as cancers. Occasionally, synthetic thyroid hormone (T4) treatment may be recommended to slow the growth of a microfollicular nodule. Close monitoring is also recommended.

• Autonomous nodules — Some nodules produce thyroid hormone, similar to the thyroid gland, but fail to respond to the body's hormonal controls. These nodules are called autonomous nodules. They are almost always benign, but they can lead to excess thyroid hormone production and hyperthyroidism.

Patients with an autonomous nodule and marked hyperthyroidism usually undergo surgery to remove the nodule, or undergo radioactive iodine treatment to destroy the nodule. If a person with an autonomous nodule has normal thyroid function or minimal hyperthyroidism, the appropriate treatment will depend on the person's age and other health factors.

This type of nodule may be monitored in young adults. However, high thyroid hormone levels pose a risk of an abnormal heart rhythm (atrial fibrillation) and bone loss (osteoporosis) with advancing age, and radioactive iodine treatment may be recommended for older adults.

• Cystic nodules — Cystic nodules are usually benign nodules that have filled with fluid. These nodules may simply collapse when the fluid is removed. Cystic nodules are usually monitored for changes; some symptoms, such as recurrent bleeding or cyst reformation require that the nodules are surgically removed.