How Is Your Thyroid?
BY AWAKE! WRITER IN BRAZIL
SARA was deeply grieved over the loss of her baby during her first trimester. About a year later, she lost another baby. Several medical tests failed to reveal the cause. As the years went by, Sara started to gain weight, even though she monitored her food intake and exercised regularly. She also developed cramps in her legs and an increased sensitivity to cold. Finally, blood tests and an ultrasound of her thyroid gland revealed that Sara had a disease called Hashimoto’s thyroiditis, a possible cause of her miscarriages.a
Like most people, Sara had rarely given thought to her thyroid. But her deteriorating health revealed just how important that gland is.
The Thyroid Gland
The thyroid is a small, butterfly-shaped gland situated in the front of the neck just below the Adam’s apple. The thyroid has two lobes that wrap around the trachea, or windpipe, and the whole gland weighs a little under an ounce. It is part of the body’s endocrine system, a group of organs and tissues that produce, store, and secrete hormones—chemical messengers—directly into the bloodstream.
The thyroid consists of numerous tiny follicles, or sacs, filled with a viscous fluid that holds the thyroid hormones. These hormones contain a high concentration of iodine. In fact, nearly 80 percent of the iodine in the body is in the thyroid. A dietary deficiency of this element may lead to an enlarged thyroid, or goiter. In young children, a lack of iodine can inhibit hormone production and thereby retard physical, mental, and sexual development—a condition called cretinism.
Thyroid Hormones at Work
The thyroid hormones are designated T3, RT3 (Reverse T3), and T4.b Both T3 and RT3 are derived from T4, the conversion largely occurring outside the thyroid in body tissues. Hence, when the body requires more thyroid hormones, the gland secretes T4 into the bloodstream, and from there the T4 and its derivatives can affect all body cells.
Just as the accelerator controls the speed of a car’s engine, thyroid hormones regulate the rate of the body’s metabolism—chemical activity in cells that produces energy and new tissue. Thus, thyroid hormones promote normal tissue growth and repair, affect cardiac rate, and maintain the production of energy for muscles and body heat.
Thyroid hormones also have other important functions. For example, they help the liver remove excess triglycerides and low-density lipoproteins, called bad cholesterol, from the bloodstream. The cholesterol is transferred to the bile and from there to the feces. On the other hand, too little thyroid hormone can cause an increase in bad cholesterol and a decrease in high-density lipoproteins, or good cholesterol.
In the gastrointestinal tract, thyroid hormones speed up the secretion of digestive juices and also increase the rhythmic waves of muscular contractions (peristalsis). Thus, too much thyroid hormone can cause frequent bowel movements, and too little, constipation.
What Controls the Thyroid?
Thyroid regulation begins in the area of the brain called the hypothalamus. When the hypothalamus detects a need for thyroid hormones, it signals the nearby pituitary gland, situated at the base of the brain above the roof of the mouth. The pituitary, in turn, releases thyroid-stimulating hormone (TSH) into the bloodstream to signal the thyroid to get busy.
Hence, by measuring blood levels of both TSH and thyroid hormones, doctors can diagnose thyroid function and health. This is important, for things can go awry.
When the Thyroid Is Not Well
Thyroid impairment may be the result of a diet poor in iodine, physical or mental stress, genetic defects, infections, disease (usually autoimmune disease), or side effects of medications prescribed for various illnesses.c An enlarged thyroid, or goiter, may be an indication of disease. The enlargement may be diffuse or in the form of nodules. Although generally benign, goiters should always receive medical attention, for they might indicate a more serious condition, such as cancer.d
Usually, ailing thyroids produce either too much or too little hormone. Overproduction is called hyperthyroidism; underproduction, hypothyroidism. Thyroid disease can develop gradually and imperceptibly, so one may have it for years and not know it. As with most illnesses, the outcome may be better if the diagnosis is made early.
The more common thyroid ailments are Hashimoto’s thyroiditis and Graves’ disease. Both are autoimmune disorders—so named because the immune system attacks normal body cells, viewing them as foreign tissue. Hashimoto’s thyroiditis is six times more common in women than in men, and it usually results in hypothyroidism. Graves’ disease is eight times more common in women and generally causes hyperthyroidism.
Opinions vary as to how often people should be tested for thyroid disease, although screening for newborns is generally felt to be important. (See the box “An Important Test for Newborns.”) If a medical examination suggests an underactive thyroid, tests for antibodies that attack the gland are usually ordered. On the other hand, if the test indicates an overactive thyroid, a thyroid scan is usually obtained, provided that the patient is not pregnant or breast-feeding. The presence of thyroid nodules may call for a biopsy to rule out malignancy.
When Treatment Is Necessary
Medication can ease the symptoms of hyperthyroidism, such as accelerated heartbeat, muscle tremors, and anxiety. Other treatment involves the destruction of thyroid cells so that the gland produces less hormones. And sometimes the thyroid may have to be surgically removed.
For patients with hypothyroidism or who have had their thyroid removed, doctors usually prescribe daily doses of the hormone T4. To get the dosage right, physicians monitor patients undergoing therapy. Thyroid cancer can be treated in a number of ways, including drugs, surgery, chemotherapy, and radioactive iodine.
Sara is successfully undergoing hormone replacement therapy with T4, and a nutritionist has helped her to plan a balanced diet. The results have been positive. As people like Sara have learned, the thyroid may be small in size, but it is big in importance. So take good care of yours—eat wholesome food that includes sufficient iodine, try to avoid chronic stress, and do your best to maintain overall good health.
a While an underactive thyroid may complicate a pregnancy, most women with thyroid disease give birth to a healthy baby. However, it is extremely important that the mother receive hormone replacement therapy, for initially she is the only source of thyroid hormone for her unborn child.
b T3 is triiodothyronine and T4, thyroxine. The digits 3 and 4 refer to the number of iodine atoms attached to the hormone. The thyroid also produces calcitonin, a hormone that helps to regulate calcium levels in the blood.
c Awake! does not endorse any particular therapy. If you suspect that you have thyroid problems, consult a physician who has experience in the prevention and management of thyroid disease.
d The risk of cancer is greater for those who have had head and neck radiotherapy or who have a personal history of cancer or relatives with thyroid cancer.
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Just as the accelerator controls the speed of a car’s engine, thyroid hormones regulate the rate of the body’s metabolism
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Thyroid disease can develop gradually and imperceptibly, so one may have it for years and not know it
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Hyperthyroidism: Excessive agitation, unexplained weight loss, rapid heartbeat, increase in bowel movements, irregular menstrual periods, irritability, anxiety, mood swings, protruding eyeballs, muscular weakness, insomnia, and thin, brittle hair.e
Hypothyroidism: Physical and mental sluggishness, unexplained weight gain, hair loss, constipation, exaggerated sensitivity to cold, irregular menstrual periods, depression, voice change (hoarseness or low voice), memory loss, and tiredness.
e Some symptoms may be caused by other underlying conditions, so be sure to consult your doctor if you feel unwell.
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AN IMPORTANT TEST FOR NEWBORNS
A few drops of blood taken from a newborn can show whether the baby has a thyroid abnormality. If blood tests reveal a problem, physicians can take corrective measures. Lacking sufficient thyroid hormones, a child may become physically and mentally retarded, a condition called cretinism. Hence, babies are usually tested just days after birth.
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ARE YOUR DIETARY NEEDS BEING MET?
Proper nutrition can help to prevent thyroid problems. For example, does your food include sufficient iodine, which is essential for the production of thyroid hormones? Saltwater fish and other seafood are excellent sources of this vital element. The amount of iodine in vegetables and meats varies according to the chemical composition of the local soil. To compensate for a lack of the element in food, some governments require that iodine be added to table salt.
Also important to the thyroid is selenium. This trace element is part of the enzyme that transforms the hormone T4 into T3. Again, the concentration of selenium in vegetables, meats, and milk depends on the soil. Seafood and Brazil nuts are rich sources of selenium. Of course, if you suspect that you have a thyroid problem, consult your doctor; do not try to treat it yourself.
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Larynx (Adam’s apple)