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List of All Topics
Hashimoto's Disease
Introduction
Hashimoto's disease causes inflammation of your thyroid, a butterfly-shaped gland located at the base of your neck, just below your Adam's apple. Although it weighs less than an ounce, the thyroid gland has an enormous effect on your health. It's part of your endocrine system, which is made up of several glands and tissues that produce hormones. These chemical messengers coordinate many of your body's activities, from digestion to metabolism to reproduction.
Hashimoto's disease is an autoimmune disorder in which your immune system inappropriately attacks your thyroid gland, causing damage to your thyroid cells and upsetting the balance of chemical reactions in your body. The inflammation caused by Hashimoto's disease, also known as chronic lymphocytic thyroiditis, often leads to an underactive thyroid gland (hypothyroidism). Hashimoto's disease is the most common cause of hypothyroidism in the United States.
Doctors use blood tests of thyroid function to detect Hashimoto's disease. Treatment of Hashimoto's disease with thyroid hormone replacement medication usually is simple and effective.
Signs and symptoms
Hashimoto's disease does not have unique signs and symptoms. The disease typically progresses slowly over a number of years and causes chronic thyroid damage, leading to a drop in thyroid hormone levels in your blood. The signs and symptoms, if any, are those of an underactive thyroid gland (hypothyroidism).
The signs and symptoms of hypothyroidism vary widely, depending on the severity of hormone deficiency. At first, you may barely notice any symptoms, such as fatigue and sluggishness, or you may simply attribute them to getting older. But as the disease progresses, you may develop more obvious signs and symptoms, including:
- Increased sensitivity to cold.
- Constipation.
- Pale, dry skin.
- A puffy face.
- Hoarse voice.
- An elevated blood cholesterol level.
- Unexplained weight gain — occurring infrequently and rarely more than 10 to 20 pounds, most of which is fluid.
- Muscle aches, tenderness and stiffness, especially in your shoulders and hips.
- Pain and stiffness in your joints and swelling in your knees or the small joints in your hands and feet.
- Muscle weakness, especially in your lower extremities.
- Excessive or prolonged menstrual bleeding (menorrhagia).
- Depression.
Causes
Your thyroid gland produces two main hormones, thyroxine (T-4) and triiodothyronine (T-3). They maintain the rate at which your body uses fats and carbohydrates, help control your body temperature, influence your heart rate and help regulate the production of protein.
The rate at which thyroxine and triiodothyronine are released is controlled by your pituitary gland and your hypothalamus — an area at the base of your brain that acts as a thermostat for your whole system. The hypothalamus signals your pituitary gland to make a hormone called thyroid-stimulating hormone (TSH). Your pituitary gland then releases TSH — the amount depends on how much thyroxine and triiodothyronine are in your blood. Finally, your thyroid gland regulates its production of hormones based on the amount of TSH it receives. Although this process usually works well, the thyroid sometimes fails to produce enough hormones.
Your immune system's role
Normally, your immune system uses naturally occurring proteins (antibodies) and white blood cells (lymphocytes) to help protect against viruses, bacteria and foreign substances (antigens) that invade your body. Hashimoto's disease is an autoimmune disorder in which your immune system creates antibodies that damage your thyroid gland. The disease causes inflammation of your thyroid gland (thyroiditis), which may impair the ability of your thyroid to produce hormones, leading to an underactive thyroid gland (hypothyroidism). Then, your pituitary gland attempts to stimulate your thyroid gland to produce more thyroid hormones, thus causing your thyroid gland to enlarge (goiter).
Doctors don't know what causes your immune system to attack your thyroid gland. Some scientists think a virus or bacterium might trigger the response, while others believe a genetic flaw may be involved. Most likely, Hashimoto's disease results from more than one factor. A combination of factors, including heredity, sex and age, may determine your likelihood of developing the disorder. Hashimoto's disease is most common in middle-aged women and tends to run in families.
Treatment
Treatment for Hashimoto's disease may include observation and use of medications. If there's no evidence of hormone deficiency and your thyroid is functioning normally, your doctor may suggest a wait-and-see approach.
Synthetic hormones
If Hashimoto's disease causes thyroid hormone deficiency, you may need replacement therapy with thyroid hormone. This usually involves daily use of the synthetic thyroid hormone levothyroxine (Levothroid, Levoxyl, Synthroid). Synthetic levothyroxine is identical to thyroxine, the natural version of this hormone made by your thyroid gland. The oral medication restores adequate hormone levels, returning your body to its normal functioning.
Soon after starting treatment, you'll notice that you're feeling less fatigued. The medication also gradually lowers cholesterol levels elevated by the disease and may reverse any weight gain. Treatment with levothyroxine is usually lifelong, but because the dosage you need may change, your doctor is likely to check your TSH level every six to 12 months.
Monitoring the dosage
To determine the right dosage of levothyroxine initially, your doctor generally checks your level of TSH after a month or two. Excessive amounts of the hormone can accelerate bone loss, which may make osteoporosis worse or add to your risk of this disease. Overtreatment with levothyroxine also can cause heart rhythm disorders (arrhythmias).
If you have coronary artery disease or severe hypothyroidism, your doctor may start treatment with a smaller amount of medication and gradually increase the dosage. Progressive hormone replacement allows your heart to adjust to the increase in metabolism.
Levothyroxine causes virtually no side effects when used in the appropriate dose and is relatively inexpensive. If you change brands, let your doctor know to ensure you're still receiving the right dosage. Also, don't skip doses or stop taking the drug because you're feeling better. If you do, signs and symptoms will gradually return.
Effects of other substances
Certain medications, supplements and even some foods may affect your ability to absorb levothyroxine. Talk to your doctor if you eat large amounts of soy products or a high-fiber diet, or if you take any of the following:
- Iron supplements including multivitamins that contain iron.
- Cholestyramine (Questran), a medication used to lower blood cholesterol levels.
- Aluminum hydroxide, which is found in some antacids.
- Sodium polystyrene sulfonate (Kayexalate), used to prevent high blood potassium levels.
- Sucralfate, an ulcer medication.
- Calcium supplements.
Information obtained from National Institute of Health