The thyroid is a small, butterfly-shaped gland measuring about 2 inches across at the base of the neck. Its sides, or lobes, lie on either side of the windpipe and are connected by a strip of tissue called an isthmus. The thyroid manufactures hormones that control metabolism, the process by which the body changes food and drink into energy.

The two main hormones produced by the thyroid are triiodothyronine (T3) and thyroxine (T4). These tell cells how much energy to use to function optimally. When the thyroid is healthy, it maintains a proper balance of T3 and T4 to keep metabolism working at the correct rate.

The amount of T3 and T4 produced is regulated by two other glands: the pituitary and hypothalamus. The pituitary gland, located at the base of the brain, is often called the “master gland” because it controls the activities of many other glands. It creates thyroid-stimulating hormone (TSH), which signals the thyroid to produce and release more or less T3 and T4.

The pituitary responds to signals from the hypothalamus, located in the brain just above the pituitary gland. The hypothalamus releases thyrotropin-releasing hormone (TRH), which controls how much TSH the pituitary releases.

Hyperthyroidism, or overactive thyroid, occurs when the thyroid makes too much T3 and T4. Hypothyroidism, of underactive thyroid, happens when there is not enough T3 or T4.

Hyperthyroidism affects between 1 and 3 percent of the US population and is more common in women. The most common cause of overactive thyroid is Graves’ disease, an autoimmune disorder in which the immune system mistakenly attacks the thyroid. Nodules on the thyroid can also cause it to be overactive.

Symptoms of hyperthyroidism include racing heart rate, restlessness, irritability, increased sweating, anxiety, trouble sleeping, thin skin, brittle hair and nails, muscle weakness, weight loss, increased appetite, frequent bowel movements and bulging eyes (common with Graves’ disease).

Diagnosing overactive thyroid typically involves blood tests that measure the levels of thyroid hormones and TSH. The doctor may give radioactive iodine and measure how much the tnyroid absorbs. The thyroid uses iodine to make hormones. If the thyroid absorbs a lot of the radioactive iodine, it’s likely overactive.

Doctors may also use an ultrasound, an imaging test that sends high-frequency sound waves through body tissues. The echoes that are created are turned into video or photographic images.

The goal of treatment for hyperthyroidism is to destroy the thyroid or block it from making its hormones. This may be done using antithyroid medications; radioiodine therapy, in which a large dose of radioactive iodine damages the thyroid; or surgery to remove part or all of the thyroid.

With hypothyroidism, the thyroid cannot produce a sufficient amount of T3 and T4. This can cause metabolism to slow down. Underactive thyroid is often caused by a condition called Hashimoto’s thyroiditis, an autoimmune disorder causing inflammation of the thyroid, surgery that removed the thyroid or damage caused by radiation treatment.

Hypothyroidism signs and symptoms include fatigue; increased sensitivity to cold; constipation; dry skin; weight gain; muscle aches, tenderness or stiffness; pain, stiffness or swelling in joints; thinning hair; slow heart rate; depression; puffy face; and horse voice.

To diagnose underactive thyroid, a doctor will perform a complete physical exam and history of symptoms. Blood tests are used to measure levels of T4 and TSH.

Treatment for hypothyroidism is hormone replacement therapy with a synthetic version of the thyroid hormones. This treatment usually involves taking the medication levothyroxine.

January is National Thyroid Awareness Month. Celebrate it by giving some thought to your thyroid.

Patti DiPanfilo

Happy New Year! I hope your holidays were joyful – and safe. January is generally the time when we set our priorities for the year. Many of us make resolutions to improve our bodies on the outside, such as losing weight. But here, we’re going to take a closer look at our bodies on the inside. Today, we’re going to think about our thyroids.

The thyroid is a gland that’s part of the body’s endocrine system. It’s responsible for making and releasing a steady amount of thyroid hormones into the bloodstream. These hormones regulate metabolism, the process of breaking down the food you eat into energy. Your metabolism affects how fast your body performs its daily functions.

Thyroid hormones regulate many body processes. These include your breathing, heart rate, body weight, temperature, cholesterol level, muscle strength and even women’s menstrual cycles. It’s important that these hormones stay at a consistent level in your bloodstream.

The thyroid is shaped a little like a butterfly and sits at the base of your throat just below your voice box. It’s about two inches long and has two lobes that lie on either side of your windpipe. The lobes are connected by a small strip of tissue called an isthmus.

The main hormones produced by the thyroid are triiodothyronine or T3 and thyroxine or T4. T3 and T4 are made by special cells called follicular epithelial cells. The thyroid also makes calcitonin in its C-cells.  Calcitonin regulates the amount of calcium and phosphorus in your blood and inhibits the breakdown of your bones.

The amount of T3 and T4 in your blood is controlled by two other glands, the pituitary in the center of the skull below the brain, and the hypothalamus in the brain. The hypothalamus produces a hormone that signals the pituitary to release its thyroid stimulating hormone (TSH). TSH tells the thyroid to release more or less T3 and T4 to maintain a balance.

When there’s an imbalance, too much or too little T3 and T4 in your blood, your body reacts. Too little thyroid hormone is a condition called hypothyroidism. It occurs when your thyroid doesn’t make enough of its hormones. Too much thyroid hormone is called hyperthyroidism.

With hypothyroidism, your metabolism slows down. Common symptoms include weight gain, sluggishness, fatigue, dry skin and hair, intolerance to cold, and depression. With hyperthyroidism, your metabolism speeds up. Symptoms include irritability, racing heartbeat, muscle weakness, weight loss and sleep problems.

There are multiple causes of thyroid disorders like hypothyroidism and hyperthyroidism. Hypothyroidism may be caused by inflammation of the thyroid gland that can lower the amount of hormones produced or by a hereditary disease of the immune system called Hashimoto’s thyroiditis. An iodine deficiency can affect the production of thyroid hormone as well.3 Removal of the thyroid also gives you hypothyroidism.

Causes of hyperthyroidism include Grave’s disease, a condition in which the entire thyroid is overactive. Sometimes, just one or a few nodules inside the thyroid produce too much hormone. Too much iodine can cause some people to have too much thyroid hormone and some to have too little.

Treatment of these disorders focuses on restoring normal blood levels of the thyroid hormones. Treatment for hypothyroidism is hormone replacement with a synthetic version in pill form. Your doctor will monitor your hormone levels with periodic blood tests and adjust your dose accordingly.

Treatment for hyperthyroidism is a little trickier. To normalize hormone levels, your doctor may use medications to block hormone production or radioactive iodine to disable your thyroid. Another treatment option is removal of the thyroid. This will give you hypothyroidism, as can the radioactive iodine. Then, you’ll have to take the hormone replacement therapy.

Thyroid disorders, including hypothyroidism, are lifelong conditions. But by following your doctor’s instructions and having your hormone levels monitored regularly, you can still live a normal, healthy life.

Hypothyroidism is a big word for underactive thyroid. “Hypo” means “beneath” or “below.” “Thyroidism” refers to the function of the thyroid. Hypothyroidism, then, means “beneath function” of the thyroid.

Hypothyroidism is a common condition. Estimates vary because millions of people have the disorder and don’t know it, but approximately 10 million Americans have the condition.

Look at it another way. About 4.6 percent of the population of the US ages 12 and older has hypothyroidism. Fortunately, most of those cases are mild. Still, that’s nearly five people out of every 100 people. Women are more likely than men to develop the disorder, and it’s more likely to occur in people age 60 and older.

Let’s learn a little more about hypothyroidism. We’ll start with the basics. The thyroid is an endocrine gland, which means it secretes its hormone directly into the blood instead of through a duct. The thyroid looks a little bit like a butterfly, and it sits in the lower front part of the neck. It produces and secretes thyroid hormones.

The thyroid controls metabolism, the process by which your body uses food for energy. If your thyroid hormone levels are lower than they need to be, which is the result of an underactive thyroid, that process can’t happen efficiently. Your body produces less energy, and your metabolism slows down.

When your metabolism slows, you may notice some changes in how you feel and function. Symptoms of hypothyroidism can be vague and are common to many other disorders, so you may not initially attribute them to hypothyroidism, but tell your doctor about them anyway. Symptoms to look out for include:

• Fatigue
• Weight gain
• Constipation
• Depression
• Dry skin
• Greater sensitivity to cold temperatures
• Muscle and joint pain
• Slower heart rate
• Swelling of the thyroid gland (goiter)

If you experience any of these symptoms, your doctor will perform a complete medical history and physical exam. If your doctor suspects hypothyroidism, he or she will order blood tests to checks hormone levels. They may include tests to measure your levels of thyroid-stimulation hormone (TSH) and T4 (thyroxine).

T4 is the main hormone made by the thyroid. TSH is made by the pituitary gland, the “master gland” in the body. TSH controls when and how much T4 the thyroid produces and releases. Lower than normal T4 levels in your blood usually mean you have hypothyroidism. People can have increased TSH with normal T4. This is called subclinical, or mild, hypothyroidism.

There are many potential causes of hypothyroidism. One is an autoimmune disorder, when the immune system mistakenly thinks the thyroid gland cells are foreign invaders and attacks them. Then there aren’t enough cells remaining to make the hormones.. The most common autoimmune disorder is Hashimoto’s thyroiditis.

Other causes of hypothyroidism include radiation treatment of the thyroid or head and neck region for cancer; inflammation of the thyroid gland; certain medications including amiodarone, lithium, interferon alpha and interleukin-2; congenital defects; surgical removal of all or part of the thyroid; too much or too little iodine, which is necessary to make thyroid hormone; and damage to the pituitary gland.

Hypothyroidism can’t be cured, but in almost all cases, it can be controlled. To treat your low thyroid hormone level, your doctor will replace what your thyroid can no longer make with a synthetic hormone, generally levothyroxine. The levothyroxine pills contain a hormone exactly like the T4  your thyroid produces on its own, so your body can function normally. Your doctor will order regular blood tests to monitor your hormone levels while on the medication.

Some people with hypothyroidism continue to have symptoms while on T4 hormone replacement therapy. They may be give a preparation with the addition of another thyroid hormone called T3. There are challenges, however, to administering T3 so that it is used efficiently and provides its full benefit. A new study out of Rush University Medical Center may have this problem solved.

The study, published in the journal Thyroid in October, offers hope to the 10 to 15 percent of hypothyroidism patients who respond poorly to standard T4 hormone replacement treatment. The study looked at a metal-coordinated molecule to assist in the absorption and metabolism of thyroid hormones.

T3 is necessary to normalize  functional hormone levels in the blood. Unfortunately, T3 metabolizes very quickly, and the body often does not get its full benefits. The goal of the study was to find a way to sustain the level of T3 in the blood so patients benefitted from the additional hormone.

A new drug was studied called poly-zinc-liothyronine (PZL); liothyronine is T3. In the study, researchers successfully treated laboratory rats that had been made hypothyroid with a tablet containing PZL. PZL is a compound made of zinc bound to three L-T3 molecules. The study showed that when researchers took T3 alone, it was immediately absorbed. PZL was not.

More research needs to be conducted before PZL is ready for widespread use. Research includes safety tests in animals and clinical trials in humans. But if you’ve got hypothyroidism that’s not responding to levothyroxine, this study offers hope. You may have a new treatment for your condition in just a few years.