You probably don’t give your thyroid much thought. It doesn’t usually demand attention like a growling stomach, a pounding heart, or a racing brain.
But this small, butterfly-shaped gland, found in the lower front of your neck, is responsible for keeping those and all other organs functioning right.
“It’s a small gland that affects nearly every cell and organ in the body,” says UNC Health endocrinologist Deepa Kirk, MD. “Thyroid hormones maintain metabolism, healthy heart function, and brain and nervous system functions. They regulate the body’s internal temperature and keep everything running.”
When your thyroid isn’t working right, your body can’t either.
Symptoms of Thyroid Dysfunction
The thyroid gland releases hormones as part of the body’s endocrine system, helping us convert food into energy, among many other functions. If there’s not enough hormone produced (hypothyroidism), you may experience fatigue, unintentional weight gain, heart palpitations, fewer bowel movements and heavier-than-usual menstrual periods. People with hypothyroidism often feel unusually cold.
If your thyroid releases too much hormone (hyperthyroidism), you may feel jittery or anxious, lose weight without trying, feel unusually hot all the time and have increased heart rate, increased bowel movements and lighter-than-usual periods.
But more often than not, a person with a malfunctioning thyroid has no symptoms.
“Often, people go to see their doctor about symptoms related to other things,” Dr. Kirk says. “If the doctor runs a thyroid test, they may pick up the disease at an early stage, where it’s not causing symptoms or the symptoms are mild. The majority of newly diagnosed cases these days are in this stage, and may not require treatment. They just need to be monitored.”
How Doctors Test Your Thyroid
When a doctor suspects a patient has thyroid disease, the first step is to test their blood for TSH, or thyroid stimulating hormone. TSH is produced in the pituitary gland and stimulates the thyroid to make thyroid hormones that circulate throughout the body.
“TSH testing is very sensitive. A very small change in the amount of circulating thyroid hormones can cause a significant change in TSH,” Dr. Kirk says. “In some cases, the TSH test is almost too sensitive. Some conditions that have nothing to do with the thyroid, like having the flu or recovering from a heart attack, can cause the TSH to transiently fall or rise out of normal range.”
Doctors can also test your blood for the amount of thyroid hormones circulating, or use a thyroid antibody test to see if your body is producing antibodies that attack your thyroid.
Another option when evaluating people with hyperthyroidism is a radioactive iodine uptake test, in which patients swallow a small capsule of radioactive iodine. Hours later, a noninvasive probe is moved over your neck to see how much iodine the thyroid absorbs. Iodine is essential in producing thyroid hormones, which is why iodine is added to some foods, especially table salt.
Thyroglobulin tests, which measure a protein made by the thyroid, are generally used to monitor people who have had surgery for thyroid cancer to see how well the treatment worked, rather than as a test of thyroid function.
Thyroid Disease Is Common, Especially in Women
An estimated 20 million Americans have some form of thyroid disease, and as many as 60 percent of them are unaware of their condition.
Thyroid disease is about seven times more common in women than in men, Dr. Kirk says. While it is found in women of all ages, occurrence increases with age. Up to 20 percent of women in their 70s and older may have abnormal TSH levels if they were tested—most mildly abnormal and not requiring treatment. Thyroid disease also can occur in children and teens as well as in men of all ages.
Hypothyroidism, or underactive thyroid, is far more common that hyperthyroidism, or overactive thyroid. The treatment is simple, effective and affordable, Dr. Kirk says. A synthetic hormone that exactly mimics thyroxine (the main human thyroid hormone) has been available for decades as a daily oral pill. However, it may take several weeks or months to get the dose right for individuals. Periodic testing is required to ensure the dose is still right.
Primary care physicians usually can diagnose and treat hypothyroidism, which affects about 5 percent of the population.
The most common cause of hypothyroidism is an autoimmune disorder called Hashimoto’s disease, in which the immune system makes antibodies that attack the thyroid gland.
Hyperthyroidism and Graves’ Disease
Hyperthyroidism is less common, affecting less than 1 percent of the population. More women than men have the disease, and it often runs in families and can affect children. It also can affect women during pregnancy.
“Doctors use the same screening tests to start,” Dr. Kirk says. “But if the TSH is low, indicating possibility of an overactive thyroid, we will do additional tests.”
Treatment for hyperthyroidism will vary, depending on what is causing the problem, she says. Often, medication is used first. Sometimes radioactive iodine treatment is used to destroy overactive thyroid cells, and in some cases, surgery is performed to remove part or all of the thyroid.
Graves’ disease, an autoimmune disease, is a common cause of hyperthyroidism in the United States. Although it may affect anyone, it is often first diagnosed in women younger than age 40. The symptoms are similar to hyperthyroidism that is caused by other factors. A key difference is that about 30 percent of people with Graves’ disease show symptoms of Graves’ ophthalmopathy, which affects the muscles and other tissues around your eyes, often causing the eyes to bulge and the eyelids to become puffy or retracted. People with this condition can experience red, inflamed eyes that are sensitive to light and feel gritty. Vision loss or double vision is possible.
Talk to Your Doctor if You Have Nagging Symptoms
If you’re gaining or losing weight without explanation, feeling too hot or too cold all the time, or experiencing unusual heartbeats or other changes to how your body works, don’t ignore it.
“If you aren’t feeling your best, talk to your doctor,” Dr. Kirk says.
Your doctor will examine you, ask you questions, and check for physical signs of illness. They’ll order appropriate blood tests, including tests of your thyroid function if needed.
“When they have the results, they’ll work with you to find the best treatment,” she says. “Thyroid problems can be treated and help you feel much better.”
Are you concerned that you have symptoms that might be caused by thyroid disease? Talk to your doctor or find one near you.