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. 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. FNA is usually performed in our office often under ultrasound guidance. 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.
 

Thyroidectomy

A thyroidectomy is an operation that removes part or all of the thyroid gland. All of the gland, or only a portion of the gland may be removed. 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 within 2 weeks of surgery.

All operations entail some risk, and thyroidectomy is no exception. All operations carry a risk of anesthesia, bleeding, and infection. The risk of needing a blood transfusion is extremely small, but all patients should avoid blood-thinning agents before surgery. Wound infections following thyroidectomy are uncommon, and are usually minor in severity.

Certain risks are 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 1-2% 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 additional surgery. Fortunately, the risk of damaging both recurrent nerves is exceedingly small.

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. All patients who undergo total thyroidectomy are observed overnight and have a serum calcium checked closely.  Most patients are started on oral calcium and Vitamin D, and are discharged the day after surgery. Fortunately, the hypocalcemia is usually always temporary- the risk of permanent hypoparathyroidism is about 2-4%.

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. Despite all the afore-mentioned complications, thyroidectomy is a very safe operation and most patients do not experience any permanent complications.

Hyperparathyroidism

The parathyroid glands are tiny glands in the neck that help to regulate the level of serum calcium. When the blood calcium level drops, the parathyroid glands release parathyroid hormone (PTH), which helps to raise the level of serum calcium. Once the serum calcium level returns to normal, PTH production usually stops. In hyperparathyroidism one or more parathyroid glands become independent and continue to produce PTH. As a result, the serum calcium climbs. The resulting hypercalcemia can result in metabolic complications such as kidney stones, osteoporosis, brittle bones that can easily fracture, and abdominal pain. The most common symptom of hyperparathyroidism is fatigue. Some patients with hyperparathyroidism are completely asymptomatic.

The diagnosis of hyperparathyroidism is made by repeated measurements of both serum calcium and PTH levels. The treatment is surgery.  The operation is performed under general anesthesia through an incision in the low anterior neck, identical to the incision used during thyroid surgery. Abnormal parathyroid glands are then identified and removed. The operation usually takes about 1-2 hours to perform, and most patients recover rapidly. Most are ambulatory on the day of surgery, and most are discharged from the hospital the morning after surgery. Most patients return to work without restriction within 2 weeks of surgery.

80-90% of hyperparathyroidism is due to a benign tumor, or adenoma, in one parathyroid gland. Removal of this one gland is therefore curative. 10-20% is due to parathyroid hyperplasia, where all glands are slightly enlarged and abnormal. Since most individuals have 4 parathyroid glands, removing 3.5 hyperplastic glands is usually curative. Rarely 2 adenomas can occur, rarer still are cancers in the parathyroid glands.

Every operation entails some risk, and parathyroid exploration is no exception. The risk of general anesthesia is small in otherwise healthy patients; a preoperative visit with your primary care physician may be beneficial for those with significant medical problems. Infections are rare, and the risk of significant bleeding is extremely small. The recurrent laryngeal nerve runs near the thyroid and parathyroid glands. Injury to the nerve on one side (very rare) will cause a breathy voice. Injury to the nerve on both sides (extremely rare) can cause breathing difficulties.

The major risk of parathyroid surgery is the risk of a negative exploration, that is, failure to remove all abnormal parathyroid glands. This risk is approximately 2-5%, meaning there is a better than 95% chance that the operation will be successful. To minimize the risk of a negative exploration, localization studies are sometimes done before surgery to try to identify which gland or glands are abnormal. The localization study most commonly performed is a nuclear scan (sestamibi scan). Although these scans are often quite useful, no test can approach the accuracy of surgical exploration.

Despite the afore-mentioned risks, parathyroid exploration is among the most successful of all surgical operations, and most patients do not experience any significant perioperative complications.