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The Powerful Little Gland That Controls Your Life

 
Understanding the Thyroid


iStock 000026573950SmallMost of us are familiar with a host of physical maladies attributed to “thyroid issues.” But do you understand what the thyroid is, or how it functions in your body? In this primer on the thyroid, we’ll shed some light on this complex and powerful little organ.


What is the thyroid and how does it work? The thyroid is a gland (glands are a collection of tissues that secrete chemicals to enable various functions in the body) located at the base of your neck, shaped like a shield or a butterfly. The thyroid secretes hormones, commonly known as T3 and T4, which regulate numerous functions including your energy level, body temperature, appetite, bowel movements, menstrual cycles, the condition of your hair, skin, and nails—even brain, nerve, and heart function are affected by the thyroid gland. Thyroid disease occurs more frequently with increased age, and it’s actually quite common among the older adults in my practice.

While a healthy thyroid will help your body function normally, the thing that makes the thyroid function normally is another little gland--the pituitary--located in the base of the brain. It releases a chemical called thyroid-stimulating hormone, or “TSH,” which regulates the thyroid and tells it what to do.

How do I know if I have a thyroid problem?
For so many reasons, it’s important to know your body and be familiar with what’s “normal” for you. If you notice a change in the way your body functions, it’s a good idea to have your thyroid checked by your physician. Thyroid problems in older adults often present differently than they do in younger people. And, since the thyroid affects metabolism in so many systems of the body, the symptoms of thyroid disease can often mimic other conditions. For instance, constipation, which can be a symptom of thyroid disease, could also have a number of other causes (such as inadequate fluid or fiber intake, decreased mobility, or side effects of medications).

To test for a thyroid problem, your physician is likely to do the following:

  • Take a medical history and talk in depth with you about the symptoms and changes you are experiencing in your body.
  • Perform a physical examination, touching the neck and perhaps asking you to swallow so they can better feel the gland’s size and texture, and determine whether it is painful to you. They may also check your skin temperature and texture, look at your eyes, and assess your heart function.
  • Order blood or imaging tests:
    • A basic blood test can reveal your TSH level. Sometimes, the results of this test can be a little bit confusing to my patients. If your TSH level is too high, it means that your thyroid is underactive (referred to as “hypothyroidism”); if the TSH level is too low, your thyroid is overactive (“hyperthyroidism”). In other words, when the thyroid is underactive and producing too little thyroid hormone, the brain produces more TSH to stimulate the thyroid back to normal. When the thyroid is overactive and producing too much thyroid hormone, the brain produces less TSH so that there is less stimulation on the thyroid.
    • A thyroid scan, often done by ultrasound, can give your physician a picture of what the structure of the gland looks like and may show abnormalities in the size or shape.

Hypothyroidism is the term we use when the thyroid is underactive. This condition is more common in my practice than overactive thyroids. Symptoms can include:

  • Tiredness/decreased energy
  • Dry skin
  • Feeling cold
  • Hair loss/thinning
  • Difficulty concentrating or poor memory
  • Constipation
  • Weight gain with poor appetite
  • Shortness of breath
  • Hoarse voice
  • Menstrual irregularity
  • Numbness or tingling
  • Swelling around the eyes

What causes hypothyroidism?

  • The thyroid requires iodine in order to function. In the U.S. we typically get enough iodine in our diets through iodized salt and foods like breads (which are fortified), dairy products, and fish. Worldwide, however, iodine deficiency is the most common cause of hypothyroidism.
  • Hashimoto’s disease is, by far, the most common cause of hypothyroidism in the U.S. This is thought to be caused by the body’s immune system mounting a reaction to the thyroid and reducing its own thyroid function. The cause for this is not fully understood, but it is clear that the thyroid is interdependent with immune system function.
  • Certain medications can have adverse effects on the thyroid.
  • Some people are born with congenital hypothyroidism, which can cause neurodevelopmental problems.
  • Some brain disorders can decrease thyroid function.
  • Treatments for hyperthyroidism, including medications, radiation therapy to suppress thyroid function, or surgical removal of part of the thyroid, can “over-correct” and result in hypothyroidism.

Hyperthyroidism occurs when the thyroid gland is overactive and can be indicated by symptoms like:

  • Hyperactivity
  • Feeling irritable, anxious, or jittery
  • Sweating
  • Chest palpitations
  • Weight loss with increased appetite,
  • Tremors or shaking
  • Diarrhea
  • Frequent urination
  • Menstrual irregularity
  • Eye movement problems, difficulty focusing eyes

What causes hyperthyroidism?

  • Grave’s disease, which is caused by an autoimmune process that over-stimulates thyroid function, is the most common cause of hyperthyroidism. Like Hashimoto’s disease, scientists are not entirely clear about the causes of Grave’s disease.
  • Bacterial or viral infections can invade the thyroid.
  • “Painless” or “silent” thyroiditis and “post-partum” thyroiditis are terms used to describe inflammation of the thyroid; these conditions are usually temporary.
  • Side effects of certain medications (including those used to treat an underactive thyroid) can cause hyperthyroidism.
  • Thyroid nodules, benign fluid-filled lumps which can form on the thyroid, can abnormally produce thyroid hormone.
  • Certain brain disorders can stimulate the thyroid to be overactive.
  • Cancer can afflict the thyroid gland.

How is thyroid disease treated? Many of the symptoms of thyroid disorders can be alleviated or even reversed through treatment. The appropriate treatment will depend, of course, on the specific type of problem you’re experiencing.
If adverse side effects of medication are the culprit, the treatment is to stop or reduce the medication. Interestingly, overtreatment of hypothyroidism is one cause of hyperthyroidism, and vice versa.

  • If an infection is causing the problem, treating the infection will usually correct the disorder.
  • Hypothyroidism is usually treated with synthetic versions of thyroid hormone, such as Levothyroxine.
  • Hyperthyroidism can be treated with medications that suppress thyroid function.
  • In some cases, radiation or surgery may be recommended.
  • Your physician will monitor the effects of treatment regularly to be sure it is working as expected. This is usually done through blood tests.

How can I keep my thyroid healthy?  Unfortunately, since science currently understands so little about some of the complex causes of thyroid disorders, there is not much that can be done proactively to prevent thyroid disease. Of course, it always makes sense to maintain a healthy lifestyle with a nutritious diet, regular exercise, good sleep, mental stimulation, and social interaction. And, be sure to have routine check-ups by a primary care physician who knows you and your history. Chances are, your primary care physician will be able to effectively treat a thyroid disorder. In some cases, I find it best to refer my patients to an endocrinologist (a gland specialist) for more specific diagnosis or treatment. Some experts recommend a routine thyroid test for healthy patients once every five years. In my practice, depending on individual circumstances, I tend to check my senior patients more frequently, particularly if they are being treated for a thyroid condition or have suspicious symptoms. If you have any new symptoms like the ones we’ve discussed here, or if your existing symptoms worsen or change, you should certainly have them evaluated by your doctor right away.

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