The thyroid gland is located in the neck, just below the larynx (voice box), and is responsible for converting iodine to thyroid hormones. Partial removal of the thyroid (usually performed in patients with papillary or follicular type thyroid cancer) puts a survivor at risk of developing hypothyroidism (a low level of thyroid hormone production). Removal of the entire thyroid renders the survivor with hypothyroidism that will require lifelong treatment. After surgery to remove part or all of the thyroid and nearby lymph nodes, tissues or organs, such as the parathyroid glands, patients may need to take medicine (thyroid hormone) and vitamin and mineral supplements (vitamin D and calcium) to replace the lost functions of these organs. In some cases, certain nerves or muscles may be damaged or removed during surgery. If this happens, the patient may have voice changes, such as hoarseness or loss of voice, or one shoulder may hang lower than the other.
Regardless of the type of surgery, once disease free, survivors should have a thyroid exam and a history and physical performed annually by their healthcare provider to evaluate for symptoms suggestive of thyroid issues, such as hypothyroidism. Survivors should be cared for either by a primary care doctor familiar with caring for thyroid cancer survivors or an endocrinologist. In addition, survivors should have a neck ultrasound initially at 6 and 12 months after treatment and then annually for 3-5 years or longer depending on stage and type of cancer. Those with metastatic disease may require imaging with CT scan or MRI. The survivor will need annual blood work to check thyroid function tests, including TSH (thyroid stimulating hormone) and T4 (thyroxine), and thyroglobulin. Bloodwork may be more frequent if the survivor is taking replacement medication (see below).
Nearly all patients who have part or the entire thyroid removed will take thyroid hormone pills to replace the natural hormone thyroxine. Survivors needing thyroxine replacement therapy, a medication called levothyroxine, may require more frequent bloodwork, initially every 6-8 or 8-12 weeks to ensure the medication dose is sufficient and then every 6-12 months once levels areregulated on medication. The goal of the medication is to suppress TSH. Therefore, it is important that the correct dose be taken and monitored. By taking levothyroxine and thus keeping TSH suppressed, the growth of any remaining thyroid cancer cells slows down, which lowers the chance of a recurrence or, in other words, the chance that the disease will return.
Levothyroxine should be taken in the morning one hour prior to eating. Levothyroxine can interact with other medications, so please check with your healthcare provider about restrictions prior to beginning any new medication. A high-fiber diet, soy-containing supplements, and walnuts can also interfere with the effects of levothyroxine. This medication seldom causes side effects when given at the correct dose. However, a few patients may get a rash or lose some of their hair during the first months of treatment. Your health care provider will closely monitor the level of thyroid hormone in the blood during follow-up visits. Too much thyroid hormone may cause patients to lose weight, become irritable, have sleep disturbances, changes in appetite, increase in frequency of bowel movements, decreased menstrual flow, tremors, muscle weakness, and to feel hot and sweaty. It may also cause chest pain, cramps, and diarrhea. These are symptoms of hyperthyroidism. If the thyroid hormone level is too low, the patient may gain weight, feel tired, fatigued, depressed, experience reduced concentration, hoarseness, joint pains, muscle cramps, constipation, menstrual cycle disturbances, feel cold, have dry skin, or brittle hair. This condition is called hypothyroidism. Survivors should report any of these symptoms to their healthcare provider.
Levothyroxine can cause problems for those with heart disease, clotting disorders, diabetes, and disorders of the adrenal or pituitary glands. Please be sure to tell your provider if you have or if you develop one of these conditions. Levothyroxine is safe to take while pregnant and breast feeding, but one may need more frequent monitoring of blood work during this time. It is important to communicate closely with your healthcare provider so that you are feeling well and the thyroid hormone replacement is managed correctly.
There are some long-term risks of continued TSH suppression. Leovthyroxine can affect the heart, causing atrial fibrillation (an irregular heartbeat) and an exacerbation of angina (chest pain) in patients with some types of heart disease. In addition, women may be at an increased risk for osteoporosis, especially those who are postmenopausal.
A survivor whose follow-up care is complicated or difficult to manage, for example a person with continued abnormal thyroid function tests or someone with new or recurrent symptoms, may benefit from referral to an endocrinologist to manage thyroid levels, replacement treatment, and on-going care.
For those with complete removal of the thyroid (thyroidectomy), or those who have received radiation and/or I-131 therapy, hypoparathyroidism can also be a lasting result of therapy. Hypoparathyroidism is a result of damage to or removal of the parathyroid glands, which are located behind the thyroid gland. Loss of these glands results in a lack of parathyroid hormone, which is responsible for regulation of calcium and phosphorus in the blood. Symptoms of hypoparathyroidism, resulting from low blood calcium, include numbness and tingling of the area around the lips, or fingers and toes, muscle cramps or spasms. Management of hypoparathyroidism includes vitamin D and calcium supplements. Monitoring of parathyroid hormone levels, blood calcium, phosphorus, and magnesium levels are required. Initially, these blood tests will be weekly to monthly and eventually will be done just twice a year. An Electrocardiogram (ECG or EKG) may be donetodetect arrhythmias (irregular heart beats) associated with low calcium levels and hypoparathyroidism. A bone density test, which evaluates the bones for osteoporosis and osteopenia, may also be conducted, often as a base-line prior to starting treatment.
A special note for survivors of Medullary Thyroid Cancer
A survivor of medullary thyroid cancer (MTC) should undergo genetic testing and counseling. One out of five MTCs results from a genetic abnormality or familial syndrome. Genetic testing can find the mutation in the RET gene seen in familial MTC and MEN-2 (multiple endocrine neoplasia type 2) syndromes. People with MEN-2 syndromes are at increased risk for development of tumors called pheochromocytoma and parathyroid adenoma. If a person has one of these mutations it is very important that his/her family is also tested including children and pre-teens. Almost all children and adults with a positive genetic test will develop MTC. Some hereditary forms of MTC affect children and young adults. It is recommended that those with a positive genetic test undergo a total thyroidectomy so as to prevent cancer from developing.
Survivors of MTC should also have additional blood work checked. Along with thyroid function tests and thyroglobulin levels, calcitonin and carcinoembryonic antigen (CEA) should be checked. If these levels begin to rise, a CT scan or MRI may be performed to determine if there is disease recurrence.
A special note for survivors of Papillary or Follicular Thyroid Cancers
Since the thyroid gland has been completely removed and ablated, a radioactive iodine scan will be done 6-12 months after the initial therapy is completed. If this scan shows no evidence of disease, most likely you will not need another scan unless symptoms or other abnormalities arise.