What is the thyroid gland?
The thyroid gland is a small gland which lies low in the middle of the neck near the windpipe (trachea). It consists of two halves each about the size of a small cherry tomato. It makes thyroid hormone called thyroxine (T4). Thyroid hormone is essential for growth, development and normal metabolism. The level of thyroid hormone is controlled by another hormone called thyroid stimulating hormone (TSH). A blood test measuring T4 and TSH will determine if someone has the correct level of thyroid hormone.
Too much thyroid hormone (hyperthyroidism):
Too much thyroid hormone may result in feeling hot, irritable, agitated and sweaty. Sometimes patients get palpitations, tremors and bulging eyes. Hyperthyroidism can be treated with medication, radioactive iodine or surgery. More about surgery later.
Too little thyroid hormone (hypothyroidism).
Too little thyroid hormone may result in feeling tired, sleepy, low in energy, cold or gaining weight. Hypothyroidism is easily treated with thyroid hormone tablets (thyroxine).
What is a goitre?
A goitre is simply an enlarged thyroid. Sometimes the thyroid gland is uniformly enlarged. Other times the thyroid gland is full of lumps (nodules), a condition called multinodular goitre. As the thyroid gland enlarges it may cause pressure on the windpipe (trachea) resulting in breathlessness on exertion or when lying down in bed at night. Other times an uncomfortable pressure feeling is felt. A big thyroid gland may stick out and look unsightly, or a big thyroid gland may enlarge behind the breast bone (sternum) - a condition called retrosternal goitre. A large goitre is usually best removed, an operation called thyroidectomy.
Thyroid nodules:
A lump in the thyroid gland is called a thyroid nodule. A lump may be noticed by the patient, the family doctor or detected on a scan. Thyroid nodules are very common. They may be single (solitary) or multiple - small or large, solid or cystic. Thyroid nodules should be investigated with an ultrasound scan. Many thyroid nodules need a small needle biopsy (FNA). This is best done with the aid of ultrasound-ultrasound guided FNA.
Management of thyroid nodules:
Thyroid nodules are very common. Thyroid cancer is not very common but also presents as a thyroid nodule. Ultrasound and ultrasound guided FNA help differentiate between benign (non cancerous) thyroid nodules and malignant (cancerous) thyroid nodules. After investigation thyroid nodules fall into three general categories - benign, intermediate (possibly malignant) and malignant (cancer). Surgery (thyroidectomy) is recommended for the intermediate and malignant categories.
Thyroid cancer:
The most common type of thyroid cancer is well differentiated thyroid cancer and consists of papillary thyroid carcinoma and follicular thyroid carcinoma. Both these cancers usually have an excellent prognosis with good long term survival and excellent function. The treatment of this type of thyroid cancer is usually total thyroidectomy and radioactive iodine (RAI). Radioactive iodine is a drink taken about three months after surgery. Any remaining thyroid cells are destroyed. If the cancer has spread to lymph nodes an operation called a neck dissection is performed. In this operation the lymph nodes in one side of the neck are removed. Decisions regarding the details of treatment are made in a multi-disciplinary meeting (MDM) where surgeons, endocrinologists, radiation oncologists, medical oncologists, radiologists and pathologists all attend. All specialities contribute to the discussion about each patient and their management. Dr Hall attends the head and neck multidisciplinary meeting at Auckland Hospital every fortnight. At the meeting we follow the American Thyroid Association 2016 guidelines on the treatment of thyroid cancer.
Medullary thyroid cancer is less common. About 20% of cases run in the family, 80% of the time it occurs spontaneously. Treatment is total thyroidectomy and central neck dissection. Patients are referred to the MDM for discussion. Medullary thyroid cancer has an intermediate prognosis. Anaplastic thyroid cancer is also uncommon. It generally, but not always, has a poor prognosis. Patients are referred to the MDM.
Thyroid surgery (Thyroidectomy):
Some thyroid conditions are treated by removing either half (hemithyroidectomy) or all (total thyroidectomy) of the thyroid. You may be referred to Dr Hall for a discussion about this option. If it is recommended that all the thyroid is removed, you will need to take thyroid hormone tablets, one or two tablets every day for the rest of your life. Periodically the thyroid hormone level will need to be checked. Once the levels are stable the thyroid levels can be checked once a year. If only half of your thyroid gland is removed thyroid tablets are not usually required. Most patients undergoing thyroid surgery stay in hospital one night and take 1 to 2 weeks off work to recover. Most patients do not find the surgery particularly painful, but it is uncomfortable. Thyroid surgery is done under general anaesthesia (GA). There are important structures near the thyroid gland. Two nerves, the recurrent laryngeal nerve and the external laryngeal nerve are near the thyroid gland. If either is injured the voice will be affected. Also next to the thyroid gland are four tiny glands called the parathyroid glands, two on each side. If these glands or their blood vessels are affected the calcium level in the blood will fall and calcium tablets will be required. Calcium tablets may be required short term or occasionally long term. As with any operation, bleeding may occur. Heavy bleeding is uncommon. As the incision is placed in a skin crease usually the healing is excellent. Long term it is frequently difficult to see where the incision has been.
Dr Hall and thyroid surgery:
Dr Hall has performed hundreds of thyroid operations. He routinely uses recurrent laryngeal nerve monitoring and the harmonic scalpel. He attends the regional head and neck multidisciplinary meeting at Auckland Hospital every two weeks where patients with thyroid cancer are discussed. He has spoken at national and international meetings on thyroidectomy and thyroid cancer and has several articles on thyroid cancer in peer reviewed international journals.