Thyroid Nodules
The thyroid gland is a butterfly-shaped gland located in the low anterior neck. It produces thyroid hormone, which helps to regulate the body’s metabolism. The functional capacity of the thyroid is measured by blood tests. Excessive production of thyroid hormone (hyperthyroidism) can cause palpitations, tremors, weight loss, and heat intolerance. Conversely, an under-active thyroid gland (hypothyroidism) can result in fatigue, weight gain, and cold intolerance.
A thyroid nodule is a growth in the thyroid gland. Thyroid nodules are extremely common, and may be solitary or multiple (multinodular goiter). It is estimated that approximately 5-10% of the population has a palpable thyroid nodule, and between 30-85% have tiny thyroid nodules that are too small to palpate.
In most people with thyroid nodules, the gland produces a normal level of thyroid hormone (euthyroid state). Statistically, approximately 5-10% of nodules are cancerous. Some patients have findings that increase the risk of malignancy. A history of exposure to ionizing radiation to the neck is such a risk factor, as is a family history of thyroid cancer. Hoarseness, lymph node enlargement, and fixation of the nodule can also increase the risk of malignancy. Fortunately, the vast majority of thyroid cancers are treatable and carry an excellent prognosis.
Most thyroid nodules do not require surgery. The primary indications for thyroidectomy are suspicion of cancer, large size, substernal location (nodules that grow inferiorly into the chest), or symptoms (throat pressure, difficulty swallowing, respiratory distress, or cosmetic disfigurement from a visible goiter). Over-functioning nodules are sometimes best treated by surgery, as well.
The most important tests to evaluate a thyroid nodule are a TSH level (a blood test that evaluates the function of the gland) and a fine needle aspiration (FNA) biopsy to evaluate the nodule for malignancy. Although FNA is highly accurate, it is not 100% accurate in making a diagnosis. There are some types of thyroid nodules (follicular tumors) where FNA cannot distinguish benign from malignant nodules- these nodules are usually best managed by thyroidectomy.
Throidectomy
A thyroidectomy is an operation that removes part or all of the thyroid gland. The most common indications for this operation are suspicion of malignancy, large nodules, substernal nodules (nodules that grow inferiorly into the chest), and nodules that cause symptoms (throat pressure, difficulty swallowing or breathing, or nodules so large they cause cosmetic disfigurement). Occasionally hyperthyroidism is treated surgically. The three most common types of thyroidectomy are total, subtotal (removes most of the gland), and hemi (removes one lobe of the thyroid). The extent of the operation depends upon the nature and extent of the pathology.
The patient is usually admitted on the morning of surgery, and the operation is done under general anesthesia. It generally takes about 1- 2 hours to perform, and is done through a horizontal incision (usually placed within a skin crease) in the low, anterior neck. Recovery is usually rapid- most patients are ambulatory the day of surgery, and most experience little or no pain after the first 24 hours. Most return to work with no restrictions after about 10 days of surgery.
Unfortunately, all operations entail some risk, and thyroidectomy is no exception. All operations carry a risk of anesthesia, bleeding, and infection. The risk of general anesthesia is often related to one’s underlying medical status, and is greater in patients with significant heart and/or lung disease. A preoperative visit with your internist or cardiologist may be beneficial for those in this situation. The risk of needing a blood transfusion is extremely small, but all patients should avoid blood-thinning agents before surgery. These include aspirin, ibuprofen, and other non-steroidal anti-inflammatory agents. Vitamin E and ginkgo biloboa are also blood thinners that should be avoided prior to surgery. Wound infections following thyroidectomy are uncommon, and are usually minor in severity. The incision will be noticeable immediately after surgery, but will usually become less visible with time. Although there will be a permanent scar, it will usually not be a very visible scar after it heals.
There are certain risks unique to thyroid surgery. The recurrent laryngeal nerve supplies the vocal cord, and this nerve must be identified and protected during thyroidectomy. Injury to one recurrent nerve causes a unilateral vocal cord paralysis which results in a breathy voice. Although this injury is rare and usually temporary, it can be permanent in about 1% of patients. If both recurrent nerves are injured (possible only in a bilateral thyroidectomy), the result is catastrophic because the vocal cords do not open during breathing. This bilateral vocal cord paralysis usually requires a tracheotomy followed by a reconstructive operation on the voicebox. Fortunately, the risk of damaging both recurrent nerves is exceedingly small.
The superior laryngeal nerve tenses the vocal cord, and is statistically injured more often than the recurrent nerve. Most individuals do not notice the injury. However, singers, will definitely notice. A superior laryngeal nerve injury can mean the end of a singing career.
The most common complication of thyroidectomy is hypoparathyroidism, or low calcium. The parathyroid glands are tiny glands in the neck that sit behind the thyroid. Although they are usually identified and protected during thyroidectomy, they often do not function properly after the surgery. It is thought that only 1 or 2 functioning parathyroid glands are needed to maintain a safe level of blood calcium. Since most people have 4 parathyroids (2 behind each lobe of the thyroid), patients having only a hemithyroidectomy are at no significant risk for hypoparathyroidism. Those that develop hypocalcemia are started on oral calcium and Vitamin D, which aids in the absorption of oral calcium. Since it often takes several days to start absorbing this calcium, these patients must remain hospitalized while they receive intravenous calcium until they begin to absorb it orally. Fortunately, the hypocalcemia is almost always temporary- the risk of permanent hypoparathyroidism is about 1%.
Patients who undergo total thyroidectomy must take thyroid hormone after surgery. This usually entails taking 1 pill daily. Since it is easy to measure the level of thyroid hormone in the bloodstream, it is usually easy to determine the necessary dose of thyroid hormone for each patient.
Some thyroid nodules are substernal, meaning they grow inferiorly into the chest. These nodules can almost always be removed through the neck, but rarely a sternotomy (division of the breastbone) is required. In addition, surgery for substernal nodules rarely results in pneumothorax, or collapse of the lung, a condition that is treated by inserting a chest tube to re-expand the lung.
Despite all the afore-mentioned complications, thyroidectomy is a very safe operation and most patients do not experience any permanent complications.