Meeting our thyroid gland
The thyroid gland is shaped like a butterfly and is located in the front of the lower part of the neck (below the larynx). It has two lateral lobes, one on the left and one on the right, connected by a tissue called the isthmus. When the thyroid is normal in size, we don’t feel it.
The thyroid gland is brownish red and richly vascular. The nerves that affect our vocalizations pass through it.
The thyroid gland produces two hormones, known as “thyroid hormones,” which doctors refer to as T3 and T4. Thyroid hormones are carried throughout the body in the bloodstream and regulate the body’s metabolism, heart rate, breathing depth, weight gain and loss, as well as controlling body temperature, cholesterol levels, and the female menstrual cycle. During infancy, adequate thyroid hormones are essential for brain development. A gland called the pituitary gland “tells” the thyroid how much thyroid hormone the body needs.
When the thyroid is “sick,” it may produce too much or too little thyroid hormone. The thyroid gland may also become larger or grow extra tissue. Thyroid disease is not uncommon; more than 12% of people will have it in their lifetime, and women are more likely to have it than men.
What are the possible diseases of the thyroid?
- Goiter. This is a general term for a swollen thyroid gland. It may be harmless, or it may be caused by an iodine deficiency or an inflammatory condition called Hashimoto’s thyroiditis.
- Thyroiditis. An inflammation of the thyroid gland, usually caused by a viral infection or autoimmune disease, that can be painful or asymptomatic.
- Hyperthyroidism (“hyperthyroidism”). This refers to an overproduction of thyroid hormones. It is often caused by Graves’ disease (an autoimmune disease) or overactive thyroid nodules. Symptoms such as irritability, weight loss, rapid heartbeat, and weakness may occur.
- Hypothyroidism (“hypothyroidism”). This refers to low production of thyroid hormones. Thyroid damage caused by autoimmune diseases is the most common cause. It slows down the body’s metabolism, which can manifest as weight gain, sluggishness, or depression.
- Thyroid cancer. A less common cancer that can be treated with surgery, radiation therapy, and hormones.
- Thyroid nodules. A small lump in the thyroid gland that is very common and, very rarely, cancerous. Nodules can produce too much hormone, which can cause hyperthyroidism, or they can be asymptomatic.
- Thyroid crisis. A rare form of hyperthyroidism, a serious condition caused by high levels of thyroid hormones.
What are the tests about the thyroid?
- Anti-thyroid peroxidase antibodies (anti-TPO antibodies). In autoimmune thyroid disease, the body’s immune proteins mistakenly attack thyroid peroxidase. This enzyme can be used by the thyroid gland to synthesize thyroid hormones.
- Thyroid ultrasound. The doctor places an ultrasound probe on top of the skin of the neck to detect abnormal thyroid tissue.
- Thyroid scan. The thyroid gland can take up iodine, and the patient takes a small amount of radioactive iodine by mouth during the test, and a thyroid imaging is performed.
- Thyroid biopsy. The doctor uses a needle to aspirate a small amount of thyroid tissue, which is usually used to diagnose thyroid cancer.
- Thyroid stimulating hormone (TSH). TSH is secreted by the brain and is responsible for regulating the release of thyroid hormones. If the blood test shows high levels of TSH, it indicates low levels of thyroid hormones (“hypothyroidism”); conversely, it indicates high levels of thyroid hormones (“hyperthyroidism”).
- T3 (triiodothyronine) and T4 (tetraiodothyronine, also called “thyroxine”): T3 and T4 are the main forms of thyroid hormones and can be checked by blood tests.
- Thyroglobulin: Secreted by the thyroid gland, thyroglobulin is used as a marker for thyroid cancer and is often used as an important reference in the follow-up of patients with thyroid cancer after treatment. If its level is too high, it indicates cancer recurrence.
- Other imaging tests: If the thyroid cancer has spread (metastasized), CT scans, MRI, and PET scans can help your doctor determine the extent of metastasis.
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What treatments are available for thyroid disease?
There is no treatment for thyroid disease.
- Thyroid surgery. This refers to surgery in which the surgeon removes part or all of the thyroid gland, and can treat thyroid cancer, goiter, and hyperthyroidism.
- Anti-thyroid medications. When treating hyperthyroidism, medications slow down the overproduction of thyroid hormones. Methimazole and propylthiouracil are common antithyroid medications.
- Radioactive iodine. Low doses can be used for thyroid screening, or to destroy overactive glands. High doses can destroy cancerous tissue.
- Extracorporeal radiation therapy. High-energy radiation helps kill thyroid cancer cells.
- Thyroid hormone tablets. After surgery to remove the thyroid gland, daily thyroxine tablets can replenish the body’s need for thyroid hormones. It can treat hypothyroidism and can also be used to prevent recurrence of thyroid cancer after treatment.
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- Recombinant human thyroid stimulating hormone. Injections may result in clearer imaging of thyroid cancer.
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