Overview
The thyroid is a small gland in the neck, shaped like a butterfly, located in front of the trachea or windpipe. Even though it is small, weighing less than one ounce, this gland is very important. The Hormone Foundation describes the thyroid’s function as regulating the body’s metabolism. Thyroid function determines whether we use the energy from foods right away or store it for later use.
Thyroid Hormones
The Hormone Foundation explains that the thyroid gland is controlled by another gland found in the brain, called the pituitary. The pituitary gland produces a hormone called thyroid stimulating hormone (TSH). The thyroid itself produces two different hormones called tri-iodothyronine (T3) and thyroxine (T4). Conditions that cause too much or too little of any of these hormones will disrupt metabolism and lead to health problems.
Types
When the thyroid gland is overactive, the condition is called hyperthyroidism; the most common form is known as Grave’s disease. When the thyroid is underactive, it is called hypothyroidism. The National Institutes of Health reports that hypothyroidism is usually caused by inflammation that damages the cells of the gland. Hashimoto’s thyroiditis, the most common type, occurs when the body’s immune system attacks the thyroid.
According to the American Thyroid Association, the term “thyroid nodule” applies to any abnormal lump or growth of the thyroid gland. While most nodules are non-cancerous, a small number may contain cancer. Thyroid cancer is rare, accounting for 10 percent or less of all nodules, and readily treatable. A goiter is an enlargement of the thyroid gland.
Risk Factors
Women are affected by several thyroid conditions more often than men, including hyperthyroidism and cancer, according to the Hormone Foundation. A genetic abnormality that tends to run in families may lead to Grave’s disease. Radiation therapy for neck cancers or exposure to radiation in the workplace may damage the gland and lead to hypothyroidism or cancer. Goiters are linked to diets low in iodine and over- or underproduction of thyroid hormone. Cancer also seems to occur more often in parts of the world where diets are low in iodine.
Symptoms
Since the thyroid regulates metabolism, symptoms depend on whether the thyroid function is increased or decreased. Common to both are changes in weight and menstrual cycles. If there is too much thyroid hormone, a person may feel nervous, have unexplained weight loss, decreased tolerance to heat and lighter than normal periods. If too little thyroid hormone is being produced, a person may feel tired and cold, have weight gain or experience heavier than normal periods. Hypothryoidism in newborns can lead to stunted growth and mental retardation. Thyroid enlargement may cause difficulty swallowing or chronic hoarseness.
Diagnosis
Lab Tests Online indicates that a TSH blood level is most often used to measure thyroid function. A higher than normal TSH may mean the thyroid is not responding to the stimulation of thyroid hormone. A low TSH may indicate an overactive thyroid or too high a dose of thyroid hormone medication. Rarely, a low TSH means that the pituitary gland is not functioning properly. If TSH is abnormal, further testing is indicated. Other thyroid lab tests include T3 and T4 levels, thyroid antibodies and calcitonin.
Thyroid scans, ultrasounds and biopsies are used to further evaluate the thyroid. An ultrasound measures the size of the thyroid. Radioactive iodine is used with a thyroid scan to create a picture of the gland. Normal thyroid tissue absorbs radioactive iodine more readily than cancerous cells. A fine needle biopsy is used to obtain samples of thyroid tissue to determine whether a nodule contains cancerous or suspicious cells.
Treatment
Treatment depends on symptoms and the presence of cancer. Cancer is usually treated by surgically removing the thyroid. Hypothyroid treatment involves synthetic thyroid hormone. Hyperthyroid treatment focuses on decreasing thyroid activity through anti-thyroid medication, radioactive iodine or surgical removal of the gland. An enlarged thyroid should be watched closely for changes in size or function, indicating the need for additional treatment.
Screening and Prevention
In the U.S., all newborns are screened for TSH, since early recognition and treatment of hypothyroidism will prevent long-term complications. Worldwide, iodine deficiency is the leading preventable cause of mental retardation, according to the Mayo Clinic. Foods higher in iodine, such as seaweed, are common in diets of people living near oceans, and may help prevent thyroid disease. Awareness of family medical history with regular screening can identify and treat Grave’s disease or thyroid cancer to minimize complications.
About this Author
Living outside of Denver, Revkah Balingit has been writing health-related educational materials since 2003. Projects have included writing and editing educational pieces for patients and professionals on a variety of health care topics. Balingit is a certified legal nurse consultant, case manager and professional of utilization management.
