Thyroid troubles
By the Mayo Clinic

You’d never know it by its small size, but your thyroid gland, which is located in your neck just below your Adam’s apple, plays a significant role in your health. Thyroid hormones regulate your metabolism―everything from the rate at which your heart beats to how efficiently you burn calories. As long as your thyroid functions normally, the fine balance of your body’s metabolism runs normally.

But if the thyroid gets off kilter, producing too much or too little of its hormones, the balance of chemical reactions in your body is upset. Symptoms may be subtle―especially in older adults―but once a thyroid problem is identified, it generally responds well to treatment.

What’s normal?
Hormones made and released by the thyroid―including the all-important hormone thyroxine―circulate in the blood. These hormones act like chemical messengers. They help control body temperature, heart rate, muscle strength, cholesterol, memory, and even your mood.

Working in conjunction with the thyroid gland are the hypothalamus and pituitary gland. These two structures in the brain help control the rate of hormone released by the thyroid. This is accomplished with the help of thyroid-stimulating hormone (TSH), which is released by the pituitary and regulates the rate at which the thyroid gland produces hormones. It’s an inverse relationship―for instance, when the blood level of thyroid hormones increases, the pituitary lowers production of TSH and that signals the reduction of thyroid hormone release.

An underactive thyroid gland (hypothyroidism) produces too little thyroxine, thus slowing the body’s metabolism. An overactive thyroid gland (hyperthyroidism) produces too much thyroxine, and so metabolism speeds up.

Underactivity is more common

The earliest symptoms of an underactive thyroid―such as sluggishness and fatigue―can be vague and even nonspecific. Too often they’re simply mistaken for getting older. As metabolism continues to slow, hypothyroidism may cause:

1. Hands or feet that feel cold all the time
2. Constipation
3. Pale, dry skin
4. Puffy facial appearance
5. Hoarseness
6. Unexplained weight gain, usually limited to 10 to 20 pounds

7. Elevated blood cholesterol level

You also may experience muscle aches or weakness, tenderness and stiffness, joint discomfort or swelling, slowed mental function, forgetfulness, and depression. Without treatment, signs and symptoms of an underactive thyroid may become more noticeable and severe. However, if you’re an older adult, you may not notice these changes.

Even though thyroid underactivity is fairly common among people over age 60, symptoms in older adults can be nonspecific and more difficult to pin down. Older people with an underactive thyroid may exhibit only one symptom, such as memory loss or decreased mental functioning. As such, it may be easily overlooked as part of aging.

In older adults, a lack of other symptoms doesn’t rule out the possibility of an underactive thyroid. Risk of a thyroid problem increases if there’s a family history of the disease, or a history of other diseases such as type 1 diabetes. Other risks include previous treatment for an overactive thyroid, a past neck surgery or radiation treatment to the neck. Simple blood tests to check for elevated TSH levels and a low level of thyroxine can identify an underactive thyroid that may warrant treatment.

The treatment of choice is the drug levothyroxine, which replaces the missing thyroxine. Periodic blood tests to check TSH levels are done over time to help determine what dose is needed. In older adults, treatment to bring thyroxine levels back to normal may take a slower course to avoid putting stress on the heart and central nervous system. The dose is typically decreased if chest pain (angina), congestive heart failure, or mental changes such as confusion occur.

Overactive thyroid

Like its counterpart, hyperthyroidism can mimic other health problems. Some of the most serious complications involve the heart and include a rapid or irregular heartbeat and congestive heart failure. Other symptoms may include unexplained weight loss, nervousness, anxiety, irritability, increased sensitivity to heat, more frequent bowel movements and an enlarged thyroid. Fatigue, muscle weakness, and difficulty sleeping may occur.

Again, in older adults the symptoms may be subtle or even unnoticeable. Most typically, you may experience an increased heart rate, heat intolerance, a tendency to tire during ordinary activities, and weight loss. Recognizing the problem can be even more challenging if you take beta blockers―such as propranolol (Inderal) and metoprolol (Lopressor) to treat high blood pressure and other conditions―because these can mask many symptoms of an overactive thyroid.

If hyperthyroidism is suspected or in question, simple blood tests can create a precise picture of how your thyroid is functioning. Treatment is geared to what’s causing the gland to malfunction. In older adults common causes are the autoimmune disorder Graves’ disease and a lumpy (nodular) goiter.

Although oral drugs can be used to reduce the level of thyroid hormones in the blood, the most common treatment involves using radioactive iodine to help throttle back the overactive gland. Taken by mouth, radioactive iodine is absorbed by the thyroid gland, shrinking it within a few months. On occasion, surgical removal of the thyroid (thyroidectomy) may be done.

Treating an overactive thyroid with radioactive iodine or surgery commonly results in the thyroid becoming underactive. If that occurs, the regular use of levothyroxine is almost always required at some point to replace normal thyroid hormones on a long-term basis. Blood test help determine the correct levothyroxine dosage.

 

Read more articles on March-April 2009 issue of Health&Home