USC Health Now

While a normal thyroid weighs less than one ounce, this small, butterfly-shaped gland has big-time responsibilities, as it impacts every organ, tissue and cell in the human body. Given the pivotal part it plays, the thyroid is frequently the fall-guy gland, blamed for everything from weight gain to general crankiness. Here, a USC expert sets the thyroid record straight.

March 3, 2008
by Carrie St. Michel

When daytime diva Oprah Winfrey speaks out—whether she’s praising an author or endorsing a presidential hopeful—people listen. So when the talk-show titan recently announced, “I blew out my thyroid,” this unassuming, 2-cm.-by-5-cm. gland was suddenly thrust into the national spotlight.

Located in the neck, wrapped around the windpipe, the thyroid produces several hormones that help cells convert oxygen and calories into energy. As a result, the thyroid can be thought of the master gland of metabolism.

In the wake of Winfrey’s thyroid revelation, many Americans were likely left with more questions than answers. As a starting point, just what did she mean by the phrase “blew out my thyroid?”

“That’s not a phrase I would use,” says John T. Nicoloff, M.D., a nationally known endocrinologist and Senior Associate Chair of Scientific Affairs, and Bernard J. Hanley Chair in Medicine at the Keck School of Medicine of USC. Based on the symptoms that Winfrey described, Nicoloff says, “It sounds like she was suffering from hyperthyroidism, followed by hypothyroidism.”

Hyperthyroidism

In describing her illness, Winfrey first complained of being “unable to sleep for days.” According to Nicoloff, “having trouble sleeping—insomnia—is certainly among the symptoms of hyperthyroidism.” The most common form of hyperthyroidism is Graves’ disease, a condition in which the immune system mistakenly attacks the thyroid gland, causing it to overproduce the hormone thyroxine. In addition to insomnia, Nicoloff says other symptoms of hyperthyroidism include:

• weight loss (despite a normal or increased appetite)
• increased perspiration
• difficulty concentrating
• hand tremors
• muscle weakness
• bulging eyes
• irregular heartbeat
• irritability/nervousness
• enlarged thyroid

Treating hyperthyroidism usually involves one of three approaches:

• drug therapy to block hormone production
• radioactive iodine treatment that disables the thyroid
• thyroid surgery (removing part or all of the gland)

On the upside, hyperthyroidism comes equipped with an endgame. “Hyperthyroidism,” Nicoloff notes, “is usually successfully treated within six months to a year.”

Hypothyroidism

“It’s not unusual,” points out Nicoloff, “for hyperthyroidism to be spontaneously followed by hypothyroidism. It’s also not uncommon for the treatment of an overactive thyroid to accelerate the subsequent development of permanent hypothyroidism.” Apparently this was the case with Winfrey, whose initial symptom of insomnia was soon trumped by excessive sleepiness.

According to Nicoloff, Hashimoto’s thyroiditis—a condition in which antibodies slowly destroy the thyroid gland’s ability to produce thyroid hormones—is the most common cause of hypothyroidism. Aside from excessive sleepiness, other symptoms of hypothyroidism include:

• weight gain (Winfrey claims a gain of 20 pounds)
• cold intolerance
• dry, coarse hair
• constipation
• dry skin
• muscle cramps
• increased cholesterol levels
• decreased concentration
• leg swelling

“While hypothyroidism is highly treatable, it involves lifelong therapy,” Nicoloff explains. Hypothyroidism is most often treated with levothyroxine—a synthetic hormone tablet that replaces absent thyroid hormones.

Diagnosis

A blood test can confirm if a person is suffering from hyperthyroidism or hypothyroidism. Nicoloff is intimately familiar with the standard test used today—called ultra-sensitive TSH—because he, along with Carole A. Spencer, M.D., professor of research, Keck School of Medicine of USC, developed the test in 1985. The test measures the level of thyroid stimulating hormone (TSH) in the blood.

Prevalence

It’s estimated that more than 20 million Americans suffer from an overactive or underactive thyroid gland, and some 50 percent of these cases go undiagnosed. Nicoloff points out that undiagnosed hypothyroidism is particularly prevalent: “When you have an underactive thyroid, you tend to slow down—you tend to gain weight. Many people assume that this is simply part of aging.”

Aging does play a role in developing a thyroid condition, as does gender. “By the time a woman is 70,” notes Nicoloff, “there’s a 20 percent chance that she’ll have a thyroid condition. The incidence in men isn’t nearly as high, although they start catching up with women as they get older. Genetics,” Nicoloff adds, “also play a significant role. If you don’t know, find out if your family has a history of thyroid problems.”

For more information on thyroid disorders, visit Medline Plus, a service of the National Institutes of Health, at: http://www.nlm.nih.gov/medlineplus/thyroiddiseases.html