The thyroid gland is a butterfly-shaped organ that sits at the front of the neck. It is composed of two lobes, left and right, connected by a narrow isthmus. It produces and releases hormones that control the body’s metabolic rate. It makes two hormones that are secreted into the blood: thyroxin (T4) and triiodothyronine (T3). These hormones are necessary for all the cells in the body to work normally.
An excess of thyroid hormone production is called hyperthyroidism. A hyperthyroid patient may experience sweating; heart palpitations; rapid heartbeat; muscle weakness; nervousness; and intolerance to warm temperatures. In contrast, hypothyroidism is a state of insufficient thyroid hormone production. Worldwide, the most common cause is iodine deficiency. Typical symptoms for hypothyroidism are abnormal weight gain, tiredness, constipation, heavy menstrual bleeding, hair loss, cold intolerance, and a slow heart rate. Hypothyroidism is managed with replacement of the hormone thyroxin.
Thyroid Disease
Disorders of the thyroid are functional, caused by dysfunction in the production of hormones, and nodes and tumors either benign or malignant. Functional disorders can cause inflammation as can some other forms of thyroiditis. Functional disorders can result in the overproduction or underproduction of hormones. Any of the functional thyroid disorders can result in the gland’s enlargement and cause a swollen neck, termed goiter.
A goiter is an enlargement of the thyroid gland that results from overgrowth. Most goiters are asymptomatic, but some can cause difficulty with swallowing or with breathing. A symptomatic goiter is usually removed surgically.
Graves’ Disease is the most common cause of hyperthyroidism. The treatment of Grave’s disease is usually medication that inhibits production of thyroid hormone, or radioactive iodine is given to reduce thyroid function. Some patients with Grave’s disease may require surgery to remove the thyroid.
Thyroid nodules are often found on the gland, with a prevalence of 4–7%.The majority of nodules do not cause any symptoms and are non-cancerous. Non-cancerous cases include simple cysts, colloid nodules, and thyroid adenomas. Malignant nodules, which only occur in about 5% of nodules, include follicular, papillary, medullary carcinomas and metastases from other sites. Nodules are more likely in females, those who are exposed to radiation, and in those who are iodine deficient.
In most cases, there is no noticeable enlargement of the thyroid and the patient is asymptomatic. Therefore, thyroid nodules are usually discovered during a routine physical exam. Even though most of them are benign, a fine needle biopsy should be performed to rule out cancer.
The most common neoplasm affecting the thyroid gland is a benign adenoma, usually presenting as a painless mass in the neck. Malignant thyroid cancers are most often carcinomas, although cancer can occur in any tissue that the thyroid consists of, including cancer of C-cells and lymphomas. Cancers from other sites also rarely lodge in the thyroid. Radiation of the head and neck presents a risk factor for thyroid cancer, and cancer is more common in women than men, occurring at a rate of about 2:1. There are a variety of thyroid cancers and they vary in how aggressively they behave. A patient with thyroid cancer or a nodule that is suspicious for cancer requires surgery for treatment.
Surgical intervention
Thyroid surgery is considered for 4 main reasons:
- You have a nodule that might be thyroid cancer
- You have a diagnosis of thyroid cancer
- You have a nodule or goiter that is causing local symptoms, like compression of the trachea, difficulty swallowing or a visible or unsightly mass
- You have a nodule or goiter that is causing symptoms due to the production and release of excess thyroid hormone: either a toxic nodule, a toxic multinodular goiter or Graves’ disease.
The extent of your thyroid surgery should be discussed by you and your surgeon and can generally be classified as a partial thyroidectomy or a total thyroidectomy.
Removal of part of the thyroid can be classified as:
- An open thyroid biopsy – a rarely used operation where a nodule is excised directly
- A hemi-thyroidectomy or thyroid lobectomy – where one lobe (one half) of the thyroid is removed
- An isthmusectomy – removal of just the bridge of thyroid tissue between the two lobes; used specifically for small tumors that are located in the isthmus
- Finally, a total or near-total thyroidectomy is removal of all or most of the thyroid tissue.
The recommendation as to the extent of thyroid surgery will be determined by the reason for the surgery. For instance, a nodule confined to one side of the thyroid may be treated with a hemithyroidectomy. If you are being evaluated for a large bilateral goiter or a large thyroid cancer, then you will probably have a recommendation for a total thyroidectomy. However, the extent of surgery is both a complex medical decision as well as a complex personal decision and should be made in conjunction with your endocrinologist and surgeon. Many thyroid surgeries require removal of only part of the gland. A person who undergoes surgery that leaves normal thyroid behind may have normal thyroid function. Other patients with more extensive surgery may require thyroid supplementation.