THYROID DISORDERS AND SURGERY
This summary is not an in-depth description of thyroid disease rather it is an informative summary of the most common thyroid conditions and treatment.
The function of the thyroid gland is to produce thyroid hormone. Thyroid hormone controls our metabolism and is regulated by other hormones to keep blood levels within a narrow range. When thyroid hormone levels are abnormal a person may experience a variety of symptoms. Symptoms may be vague, mild, and difficult to notice if hormone levels are only slightly abnormal. If more significant abnormalities exist, health is threatened and mortality is increased.
ANATOMY AND FUNCTION
The thyroid gland is an organ located in the lower neck below the larynx and wraps around the trachea or windpipe. The gland is divided into right and left lobes connected in the middle by a band of tissue called the isthmus. A normal thyroid gland is not visible and may even be difficult to feel. The thyroid gland produces two types of thyroid hormone, T4 and T3. T4 is produced in greater quantities and is converted in the body to T3. T3 is the active hormone which affects our organs. The thyroid gland is controlled by a hormone called Thyroid Stimulating Hormone or TSH, which is produced by the pituitary gland located at the base of the brain. Thyroid Stimulating Hormone is produced in higher quantities when the pituitary gland senses low levels of thyroid hormone in the blood and it stops producing TSH when blood levels of thyroid hormone are high. In a normal person, TSH, T4, and T3 hormone levels should be within a narrow range and this condition, the normal condition, is called euthyroid. When too much T4 or T3 hormone is produced or exists in the body, a person is hyperthyroid; when levels are too low they are hypothyroid. TSH levels are low when a person is hyperthyroid because the high levels of T4 and T3 cause the pituitary gland to decrease the amount of TSH hormone production. When T4 or T3 blood levels are low, TSH is high, as the body tries to stimulate the thyroid gland to produce more hormones. In some cases a person has high or low TSH levels, but T4 and T3 are normal. This is considered sub-clinical disease and these people usually progress to true hyperthyroidism or hypothyroidism over time.
Most abnormal thyroid conditions fit within two divisions: hormone abnormalities or thyroid masses and these conditions may be related as some thyroid masses may affect hormone levels.
Hormone abnormalities are suspected when a person has symptoms of either increased or decreased hormone levels. Some typical symptoms and findings related to hormone imbalance are listed below.
SYMPTOMS OF HYPOTHYROIDISM
Weight gain, fatigue, tiredness, sleep apnea, hair loss, thin eyebrow hair, cold intolerance, infertility.
SYMPTOMS OF HYPERTHYROIDISM
Weight loss, tremor, nervousness and anxiety, heart palpitations, heat intolerance, sweating, diarrhea, infertility, prominent eyes.
When a person is thought to have thyroid hormone abnormalities, a careful exam of the thyroid and neck is performed. In most if not all cases the larynx will be examined to verify vocal cord function. Blood tests are ordered to check TSH, T4, and T3 or just TSH, as it is a cost effective way of screening for disease. If tests show increased levels of T4 or T3 and decreased levels of TSH, they are hyperthyroid and the next concern is why. If they also have symptoms of hyperthyroidism they are considered to have thyrotoxicosis, which is important as the risk of mortality is increased. It may be that the whole thyroid gland is abnormal and producing too much hormone, or one hyper functional nodule exists, or they are taking too much thyroid hormone, or they are eating various foods that stimulate the thyroid gland to produce too much hormone (iodine containing foods or materials).
A test may be ordered called a thyroid uptake scan. This test is performed at the hospital by the radiology department. A material containing Iodine with low dose radiation is injected into the bloodstream. Virtually all iodine that enters our body is taken up by the thyroid gland. The Iodine based material accumulates in the thyroid gland and X-rays are taken of the neck. If the whole thyroid gland is abnormal the radiology images will show a gland with increased signal intensity which is typical for Grave's Disease and Hashimoto's Thyroiditis. If one area of the gland shows increased intensity and the remaining gland is normal or shows low intensity, a hyper functional nodule or mass is present called a toxic nodule. Sometimes an area of decreased uptake is present which may indicate a cystic mass or malignant tumor.
Treatment of hyperthyroidism varies depending upon the condition and degree of symptoms but may include medications, radiation therapy, or surgery. The most common treatment for Grave's disease is with radioactive iodine, which causes the thyroid cells to die. Treatment of thyroiditis is variable as the condition often causes increased hormone levels early in the disease course, but ultimately hypothyroidism requiring thyroid hormone medication results. Toxic nodules may be treated with radiation which affects the whole gland or with surgical excision of the nodule, preserving the remaining normal gland tissue. The best treatment for these conditions is determined by your specific condition.
Treatment of hypothyroidism is with medication. The majority of people have thyroiditis but iodine deficient diets were once a major cause for the condition. Blood tests (thyroid peroxidase, anti-thyroid antibodies) are available which may be used to diagnose thyroiditis. Many people with thyroiditis also have gluten sensitivity. The proper dose of medication is important and is determined by repeat blood tests until normal function is achieved. A variety of medications are available including Synthroid, levothyroixine, and Levoxyl to name a few. Other varieties of hormone have been used including Armour thyroid, which is taken from a pig thyroid gland, but this hormone is not FDA regulated and the amount of hormone taken per dose varies. The type of hormone prescribed and the dose will be determined by the patient's needs and the doctor. It is extremely important for pregnant women to take the proper dose of hormone as children born with low hormone levels are at increased risk of brain dysfunction and cretinism.
THYROID MASSES AND NODULES
A thyroid goiter refers to an enlarged thyroid gland. The term is still used but was more commonly used when iodine deficient diets were common and gland enlargement was endemic. Since iodine was added to salt, this cause of goiter has become uncommon in the United States. The entire thyroid gland may become enlarged when diseased or failing because the tissue grows in order to produce more hormones. In some cases an enlarged gland is normal such as during pregnancy.
A multinodular goiter is a common cause for thyroid enlargement and in this condition multiple nodules are present within the gland and the nodules vary in size from 1 mm to very large. This condition is often associated with hypothyroidism but may cause hyperthyroidism. A concern in those who have a nodular goiter is that the gland may become large enough that structures in the neck are compressed. Large thyroid glands may affect breathing and swallowing which may become a threat to life. These large glands are often removed to improve function, relieve compression, or remove an unsightly mass in the neck.
Thyroid glands with a dominant nodule or mass are a particular concern. Even though many nodules may be present, if one nodule is larger, it is worrisome because of the risk of a tumor is increased. Thyroid tumors may be benign or malignant with about 10% being malignant. The most common type of nodule is a benign colloid nodule. Colloid is the material used as a substrate for hormone production. Other types of masses include cysts, which are fluid filled masses and are usually benign. Adenomas are tumors and although benign will continue to grow. Malignant masses are the main concern when a dominant nodule is present and this is why additional testing is needed when a dominant thyroid nodule is present.
The best way to investigate a dominant nodule is with a thyroid ultrasound. This simple test will show the size and character of the mass and gland. Certain features which may be seen on ultrasound imaging are worrisome for cancer such as indistinct borders, increased blood flow to the lesion, and calcium particles within the nodule. Ultrasound is also used routinely to determine if abnormal lymph nodes are present in the neck as thyroid cancer may spread. Some doctors will order a thyroid scan which is intended to show if the nodule is functional. Active "hot" nodules are thought to be benign and "cold" nodules that do not uptake material are more likely but not usually malignant. This test is not reliable and only provides limited information. CT scan and MRI scans are useful for large glands to see if they extend into the chest and to determine if abnormal lymph nodes are present in the neck.
After or during the ultrasound, it is standard to obtain a biopsy of the dominant nodule using a needle. Fine needle biopsy is a simple method to obtain tissue and is very accurate in diagnosing some types of thyroid cancer. It may be performed in the office with or without ultrasound to guide the needle. Needle biopsy results are reported by a cytopathologist which is a specially trained pathologist. Results are reported as benign, indeterminate, or malignant. It is important to understand that needle biopsy is most accurate when it shows cancer cells, as it is almost always true. If the biopsy does not show cancer cells it is also usually true, but it may not reflect the true composition of the mass or the pathologist may not be able to tell if the cells are not abnormal enough to diagnose cancer.
Benign lesions do not require immediate additional treatment unless they are large and cause compression of the neck or are a cosmetic concern. A repeat ultrasound and follow-up is still required to monitor the growth of the mass or nodule. About five percent of nodules read as benign are actually cancers. Enlarging masses and nodules may require another biopsy if worrisome.
Biopsies that show indeterminate results should be repeated with ultrasound guidance or by surgery to remove the nodule. In some cases monitoring the gland with ultrasound to see if the nodule grows can be done. Additional testing with Veracyte Afirma genetic testing is another option. This technology can provide information about the tissue. Forty percent of nodules that are positive on genetic testing are cancer. If genetic testing shows negative results, about five percent have cancer.
Nodules which are suspicious or show cancer cells are removed surgically. Surgery is described below in more detail. Nodules which show follicular cells are a special condition. The most common type of cancer is papillary thyroid cancer. Papillary thyroid cancer has specific cell features and may be identified accurately with needle biopsy. Follicular cell cancer is the second most common type of thyroid cancer but follicular cell adenoma is an even more common condition and is not a cancer. There may be subtle features that support a follicular cell cancer, but in order to prove that the lesion is cancer the pathologist must confirm invasion of abnormal cells through a capsule that surrounds the mass. This is not possible with a needle biopsy. Follicular lesions are usually removed by surgery to determine if a cancer exists.
Thyroid surgery has been performed for many years but with improvements in technology, surgical technique has evolved. Many surgeons perform thyroid surgery but the techniques used and the number of cases each surgeon performs per year varies greatly. Studies show that surgeons who perform high volume thyroid surgery have the fewest complications rates. Dr. Douglas Denys is a high volume thyroid. The standard method to remove the thyroid gland is through an incision in the lower neck. The size of the incision can vary from under one inch to over 4 inches. Thyroid surgeons trained in minimally invasive technique are best able to perform thyroid surgery through small incisions which reduces the risk of injury and complications, results in less time off work and faster recovery, and a better cosmetic appearance of the neck. It is typical for less experienced surgeons to use long incisions as surgical exposure is easier. Dr. Denys is the only surgeon at American Fork Hospital who has performed endoscopic thyroid surgery, a more complicated and the least invasive technique for thyroid surgery used in select patients.
The standard thyroid surgery is as follows: The patient is admitted through outpatient surgery to the hospital. The surgery typically takes 60 minutes to 120 minutes depending upon if one half or if the entire gland is removed and if pathology is required during surgery. An incision is created in the lower neck. Dr. Denys will often draw the planned incision on the neck before surgery in order to place it within a wrinkle line or the most cosmetic location. An average incision is 1.5 inches but this depends upon the size of the thyroid mass. The patient will be taken to the operating room and given medications to produce general anesthesia. The anesthesia team uses a special tube for breathing during surgery which is also a nerve monitor (NIM monitor). It will provide a signal if the vocal cord nerve is near and reduces the chance of nerve injury. Two wires attached to needles are placed into the skin in the midline of the chest. This does not usually hurt but puncture marks in the middle of the chest will be present after surgery. It is important to know that a nerve monitor is not a substitute for surgical experience but in select cases it provides information that may reduce the chance of nerve injury.
Once the incision is created, the thyroid gland is exposed and the tissues are dissected in a careful and precise manor. Extreme care and meticulous dissection is very important to reduce pain, swelling, and injury of important structures. Blood vessels which supply the thyroid gland are identified as are the laryngeal nerves and parathyroid glands. Once all structures are confirmed and known to be safe, the gland is removed. If pathology confirms a benign condition the incision is closed. If the pathologist confirms cancer, total gland removal is performed as well as lymph node dissection. Lymph nodes are removed in the area around the thyroid as this is the first and most likely place for cancer to spread. Dr. Denys is trained in plastic surgery and will close the incision in a way to give the best cosmetic results possible. Most patients who have one side of their thyroid gland removed will be discharged home the day of surgery. It is more common for those who have had the entire gland removed to stay in the hospital overnight but it is very uncommon to stay in the hospital for more than one night. In specific patients a drain will be used but this is uncommon and usually only used in patients with very large tumors. A sterile bandage will be placed on the incision which will permit showering and most activities immediately after surgery.
POST-OPERATIVE CARE AND ACTIVITIES
After surgery it is best to sleep the first night with your head elevated above your heart as this will decrease swelling and pain. Light activities are permitted but heavy lifting and exercise should not be done for one week. You may shower after surgery with the bandage in place. The bandage may be removed in three days but leave the strips of tape over the incision in place. You may eat anything you wish but begin with liquids and advance to solids as tolerated. Do not take Aspirin or Motrin after surgery as these drugs may increase the risk of bleeding in the neck. A follow-up appointment is planned one week after surgery with Dr. Denys.
Thyroid hormone replacement
If total thyroidectomy was performed, thyroid hormone replacement will be required forever. If hormones are not taken, symptoms of hypothyroidism will occur which will reduce quality of life and increase mortality. Hormone levels will be tested in two to four weeks after surgery and then hormones will be started or adjusted as required until proper levels have been achieved.
If partial thyroidectomy was performed, the need to take thyroid hormones after surgery varies. Most people, about 70%, who have normal thyroid hormone levels before surgery will still have normal levels after surgery and will not require hormone therapy. Some people have normal hormone levels before surgery but have a diseased gland that is barely able to produce enough hormones for proper function. After removal of one thyroid lobe, if the remaining lobe is unable to produce enough hormones thyroid hormone levels will fall and hormones will be needed. A blood test for thyroid hormones is obtained three to four weeks after surgery.
Need for additional surgery
The surgical plan is known in advance for most patients but some have undiagnosed disease. In these patients removal of the mass is planned by removing the lobe of the thyroid which contains the mass. The specimen is then examined by the pathologist. If the pathologist confirms cancer, total gland removal is planned. In some cases, especially follicular cell tumors, the pathologist will not give a final diagnosis and will defer their opinion to final processing. If a cancer is confirmed by, a second operation may be indicated to remove the remaining thyroid gland. This happens in about 5% of patients.
After thyroid lobotomy the gland should not re-grow unless a significant remnant is left. In some cases this is done on purpose to prevent injury to the nerve, especially when scar tissue is present. Re-growth on the operative side is very uncommon. In some patients the opposite side will grow over time. The lobe may have been left because it was normal and because it was still active and able to produce thyroid hormone. In these patients, the decision to remove the remaining lobe depends upon the same indications as above-a large nodule or one which is suspicious for cancer.
Thyroid cancer treatment is a complex topic. Surgical treatment by thyroidectomy, either one lobe or total gland removal is the typical treatment. If a cancer is known at the time of surgery lymph nodes are also removed to see if cancer has spread from the thyroid gland to other sites. Once surgery has been performed tests are obtained to plan for additional treatment. Please see the separate discussion on thyroid cancer.
Although most patients have uneventful surgeries, there are a number of important structures in the neck near the thyroid gland and these structures are at risk of harm and injury. The most important structure is the recurrent laryngeal nerve. There is one nerve on each side of the larynx which passes under the thyroid gland. This nerve controls the muscles of the larynx and each nerve controls one half of the larynx. If the nerve is injured the voice may be altered temporarily or permanently. If the nerve is stretched, compressed, or bruised the nerve will not work for a period of time and then it will recover, usually with normal function. If the nerve is cut, the nerve will never work and the voice will never be normal. The consequence of a nerve injury is an altered voice, breathing difficulties, and abnormal swallowing. The voice will be breathy and weak if the nerve is injured. It may be difficult for a person to swallow and liquids may enter the trachea causing coughing. If both nerves are injured, during total thyroidectomy, breathing is almost always a concern and may require emergency treatment with a tracheotomy tube placed into the neck. This is a serious injury. These serious complications should be exceptionally uncommon but the rate of a single nerve injury is reported between one and five percent. This complication rate varies depending upon the experience often the surgeon. A surgeon with less experience or a surgeon who does not do a consistent volume of thyroid surgery has been shown to have higher complication rates. However, nerve injury does occur even with the most experienced thyroid surgeons.
Low calcium levels
The parathyroid glands are located around the thyroid gland. Four glands are present in most people with two glands on each side. Each gland is about the size of a lentil bean or a small apple seed. Parathyroid glands produce parathyroid hormone which regulates the amount of calcium in the blood. Calcium is important and if the parathyroid glands are removed or damaged, calcium levels in the blood will drop. Removal of a parathyroid gland or injury may occur during thyroid surgery and if this occurs, symptoms of low calcium may occur. Symptoms begin with tingling of the face in the region around the mouth and nose. Generalized weakness and increased numbness and tingling occur as calcium levels become lower. Nerves become more excitable and if calcium levels become too low, seizures and heart rhythm abnormalities may also occur. If the glands were damaged, they usually recover but calcium pills and vitamin D pills are used for several weeks after surgery. If all four parathyroid glands were removed, calcium supplements will be required forever and certain activities may be adversely affected like exercise tolerance as muscle cramping is more common. Low calcium levels due parathyroid gland injury is much more common in those who have total thyroidectomy, patients with cancer, and those with thyroiditis because all four glands are at risk of injury.
This may happen after any surgery but is very uncommon. Total blood loss during thyroid surgery should be minimal. Not only is surgery easier when there is less bleeding but it often indicates better technique. It is possible to have delayed bleeding into the neck after surgery which may require intervention by the doctor. It is best to stay in an area which is safe for the first week after surgery and refrain from exercise and heavy lifting and do not take blood thinning drugs like Aspirin, Motrin, or Excedrin.