What is the thyroid gland?
Gland refers to an organ in the body that secretes hormones (substances that help regulate different body functions) into the bloodstream. All glands are part of the endocrine (gland) system. The thyroid gland secretes thyroid hormones.
Where is the thyroid gland located?
The thyroid gland is located just below the larynx (voice box) or “Adam’s apple” in the front of the neck. In some thyroid diseases, the thyroid gland enlarges (goiter), which can be felt and seen as a bump in the neck. Sometimes, the first sensation with thyroid enlargement is a feeling of fullness or difficulty swallowing.
What hormones are secreted by the thyroid gland?
There are three types of thyroid hormones secreted by the thyroid gland:
Thyroxine (T4), iodothyronine (T3), and calcitonin.
What do thyroid hormones do in the body?
Both T4 and T3 are involved in energy regulation in the body (metabolism).
In children, normal levels of T4 and T3 are very important in normal growth and brain development.
Calcitonin is involved with keeping a normal level of calcium (a substance found in bones and teeth, among other places) in the bloodstream. It works closely with the hormone secreted by the PARATHYROID GLAND.
What problems can develop with the thyroid gland?
Abnormal conditions involving the thyroid gland include a localized enlargement (nodule) or overall enlargement (goiter) of the thyroid gland. Thyroid nodules and goiters can result in normal levels of thyroid hormone (euthyroid), too much hormone (hyperthyroid), or too little thyroid hormone (hypothyroid) in the bloodstream.
Infections or inflammation of the thyroid gland may also occur which usually results in hyperthyroidism first, followed by hypothyroidism. For more information, please see THYROIDITIS discussed later in this topic.
When the thyroid gland produces too little hormone, the condition that results is called hypothyroidism. The symptoms noticed most commonly include being very tired, hair loss, gaining weight for no reason, and constipation among others.
In newborns, the lack of thyroid hormone results in a condition called cretinism; the child grows up mentally retarded and with growth deformities. Because of this, all newborns in the United States are screened for hypothyroidism to help prevent this condition. Hypothyroidism can also be acquired later in life if the body produces abnormal cells (antibodies) that can damage the thyroid gland (Hashimoto thyroiditis). Hashimoto’s thyroiditis is usually accompanied by a goiter (enlargement of the thyroid gland).
What is the treatment for hypothyroidism?
Hypothyroidism is treated by taking thyroid hormone medications (levothyroxine and liothyronine). Too little iodine (a mineral needed to make thyroid hormone) may also cause low thyroid hormone levels and increasing iodine in the diet may also be necessary. Iodine deficiency is rarely seen today in the United States because iodine is found in our table salt.
What is hyperthyroidism?
Hyperthyroidism is the condition that results when too much thyroid hormone is in the bloodstream. Symptoms associated with this condition include anxiety, heart palpitations (heart “racing”), sweating, weight loss for no apparent reason, and diarrhea among others.
How is hyperthyroidism treated?
Hyperthyroidism can be treated in different ways depending on why the thyroid is overactive and the age of the patient.
The patient may be treated with some medications that decrease the production of thyroid hormone or by surgical removal of part of the thyroid gland (THYROIDECTOMY).
What are some of the causes of a hyperactive thyroid gland?
The most common cause of hyperthyroidism in children is a condition is called Graves’ disease. It is a condition in which the body produces abnormal cells (antibodies) that result in the thyroid gland’s overproduction of thyroid hormone.
The diagnosis is usually made by symptoms of hyperthyroidism, and confirmed with special blood tests specific for this disease. In children, it is usually treated with medications first. However, if medications are not effective, the thyroid gland may have to be destroyed with radioactive iodine. If that is not an option, surgical removal (SUBTOTAL THYROIDECTOMY) may be considered.
Thyroiditis is tenderness and inflammation of the thyroid gland. While the thyroid is inflamed, excessive thyroid hormone can be released, resulting in hyperthyroidism. After the hyperthyroid stage resolves, there may also be a period of hypothyroidism. There are two types of thyroiditis:
Severe pain, and swelling around the thyroid gland and fever is known as acute suppurative thyroiditis. It is usually caused by a bacterial infection. Ultrasound can be used to look for abscesses (collections of pus). Treatment consists of antibiotics (usually given by a vein at the start of treatment), and possible surgical drainage or thyroid LOBECTOMY if an abscess is found.
A less severe form of thyroiditis is known as subacute thyroiditis. It is usually caused by a virus and presents with a low-grade fever, mild pain and tenderness in the area of the thyroid gland, and minimal enlargement of the thyroid gland.
This diagnosis is sometimes confused with Graves’ disease, but a thyroid scan can differentiate the two. Subacute thyroiditis usually resolves without treatment although supportive measures (fluids, rest and pain medicine) may make the patient more comfortable.
What are thyroid nodules?
A thyroid nodule is basically an abnormal lump in the thyroid gland. It may be felt or seen as an abnormal bump in the neck, or may produce symptoms such as hoarseness, or difficulty swallowing. As mentioned above, thyroid hormone levels can be normal, elevated, or decreased depending on the type of nodule.
Thyroid nodules most commonly are benign (not cancerous). Examples of these types of nodules include adenomas (overgrowth of thyroid tissue) and thyroid cysts (nodules containing fluid). Often, a thyroid cyst can simply be drained. If it recurs, it is usually surgically removed, as is a thyroid adenoma.
Thyroid cancer is much less common, and the overall prognosis is good. There are different types of thyroid cancer, which affects the prognosis. Thyroid cancers such as Papillary and Follicular generally have a better prognosis than Medullary and Anaplastic. However, treatment almost always consists of a THYROIDECTOMY as well as radioactive iodine destruction of any remaining thyroid tissue. Your surgeon will go over your child’s diagnosis and specific treatment in detail.
How are thyroid nodules evaluated?
The most important thing to determine in an evaluation is whether the nodule contains cancer. There are specific characteristics that a nodule has making it suspicious for cancer. Once a nodule is determined to be suspicious for cancer, a fine needle aspiration biopsy (FNA) is performed. This consists of inserting a needle into the nodule to determine what types of cells are present (a type of cancer cell, suspicious cells, or normal cells). However, this procedure is invasive and other studies are usually performed before this to decide which nodules should be biopsied.
A careful history of symptoms, a complete family and patient history and a thorough physical examination of the thyroid gland is initially performed. This is usually followed by blood tests that determine if the thyroid hormone levels are high, low, or normal.
Next an ultrasound is used to determine if the nodule is solid (contains tissue), cystic (contains fluid), or a combination of both. A cystic nodule is more likely to be non-cancerous. Finally, a thyroid scan is used to determine if the nodule is overactive (hot), active (warm), or under active (cold) compared to normal thyroid tissue. Cold nodules are more likely to be associated with cancer.
Once a fine needle aspiration biopsy is taken, the cells are examined to determine what further treatment is indicated. If cancer cells or suspicious cells are found, a THYROIDECTOMY is indicated.
Who can treat diseases of the thyroid gland?
Most commonly, non-surgical diseases of the thyroid gland are managed by an endocrinologist (a physician specializing in the glands in the body) or another physician who is experienced in managing the thyroid hormone medications and levels in the body.
Because of its location in the neck, an otolaryngologist is consulted when surgery of the thyroid gland (THYROIDECTOMY) is indicated.
Thomas M. Andrews
Dr. Andrews specializes in the medical and surgical treatment of ear, nose and throat disorders of children and adolescents. His accreditations include Florida State Medical License and Ohio State Medical License. He is also a board member of the National Board of Medical Examiners and American Board of Otolaryngology, Head and Neck Surgery