Hashimoto's disease

A number of conditions may lead to the signs and symptoms of Hashimoto's disease. If you're experiencing any of these symptoms, your health care provider will conduct a thorough physical exam, review your medical history and ask questions about your symptoms.

Testing thyroid function

To determine if hypothyroidism is the cause of your symptoms, your provider will order blood tests that may include the following:

• TSH test. Thyroid stimulating hormone (TSH) is produced by the pituitary gland. When the pituitary detects low thyroid hormones in the blood, it sends thyroid-stimulating hormone (TSH) to the thyroid to prompt an increase in thyroid hormone production. High TSH levels in the blood indicates hypothyroidism.
• T-4 tests. The main thyroid hormone is thyroxine (T-4). A low blood level of thyroxine (T-4) confirms the findings of a TSH test and indicates the problem is within the thyroid itself.

Antibody tests

More than one disease process can lead to hypothyroidism. To determine if Hashimoto's disease is the cause of hypothyroidism, your health care provider will order an antibody test.

The intended purpose of an antibody is to flag disease-causing foreign agents that need to be destroyed by other actors in the immune system. In an autoimmune disorder, the immune system produces rogue antibodies that target healthy cells or proteins in the body.

Usually in Hashimoto's disease, the immune system produces an antibody to thyroid peroxidase (TPO), a protein that plays an important part in thyroid hormone production. Most people with Hashimoto's disease will have thyroid peroxidase (TPO) antibodies in their blood. Lab tests for other antibodies associated with Hashimoto's disease may need to be done.

Most people with Hashimoto's disease take medication to treat hypothyroidism. If you have mild hypothyroidism, you may have no treatment but get regular TSH tests to monitor thyroid hormone levels.

T-4 hormone replacement therapy

Hypothyroidism associated with Hashimoto's disease is treated with a synthetic hormone called levothyroxine (Levoxyl, Synthroid, others). The synthetic hormone works like the T-4 hormone naturally produced by the thyroid.

The treatment goal is to restore and maintain adequate T-4 hormone levels and improve symptoms of hypothyroidism. You will need this treatment for the rest of your life.

Monitoring the dosage

Your heath care provider will determine a dosage of levothyroxine that's appropriate for your age, weight, current thyroid production, other medical conditions and other factors. Your provider will retest your TSH levels about 6 to 10 weeks later and adjust the dosage as necessary.

Once the best dosage is determined, you will continue to take the medication once a day. You'll need follow-up tests once a year to monitor TSH levels or any time after your provider changes your dosage.

A levothyroxine pill is usually taken in the morning before you eat. Talk to your doctor if you have any questions about when or how to take the pill. Also, ask what to do if you accidentally skip a dose. If your health insurance requires you to switch to a generic drug or a different brand, talk to your doctor.

Precautions

Because levothyroxine acts like natural T-4 in the body, there are generally no side effects as long as the treatment is resulting in "natural" levels of T-4 for your body.

Too much thyroid hormone can worsen bone loss that causes weak, brittle bones (osteoporosis) or cause irregular heartbeats (arrhythmias).

Effects of other substances

Certain medications, supplements and foods may affect your ability to absorb levothyroxine. It may be necessary to take levothyroxine at least four hours before these substances. Talk to your doctor about any of the following:

• Soy products
• High-fiber foods
• Iron supplements, including multivitamins that contain iron
• Cholestyramine (Prevalite), a medication used to lower blood cholesterol levels
• Aluminum hydroxide, which is found in some antacids
• Sucralfate, an ulcer medication
• Calcium supplements

T-3 hormone replacement therapy

Naturally produced T-4 is converted into another thyroid hormone called triiodothyronine (T-3). The T-4 replacement hormone is also converted into triiodothyronine (T-3), and for most people the T-4 replacement therapy results in an adequate supply of T-3 for the body.

For people who need better symptom control, a doctor also may prescribe a synthetic T-3 hormone (Cytomel) or a synthetic T-4 and T-3 combination. Side effects of T-3 hormone replacement include rapid heartbeat, insomnia and anxiety. These treatments may be tested with a trial period of 3 to 6 months.

Products with T-3 and T-4 hormones derived from pigs or other animals are available as prescriptions or as dietary supplements, such as Armour Thyroid, in the United States. Concerns about these products include the following:

• The balance of T-4 and T-3 in animals isn't the same as in humans.
• The exact amount of T-4 and T-3 in each batch of a natural extract product can vary, leading to unpredictable levels of these hormones in your blood.

You're likely to start by seeing your primary care provider, but you may be referred to a specialist in hormone disorders (endocrinologist).

Be prepared to answer the following questions:

• What symptoms are you experiencing?
• When did you start experiencing them?
• Did your symptoms begin suddenly or develop gradually over time?
• Have you noticed changes in your energy level or your mood?
• Has your appearance changed, including weight gain or skin dryness?
• Have your bowel habits changed? How?
• Do you have muscle or joint pain? Where?
• Have you noticed a change in your sensitivity to cold?
• Have you felt more forgetful than usual?
• Has your interest in sex decreased? If you're a woman, has your menstrual cycle changed?
• What medications do you take? What are these medications treating?
• What herbal remedies, vitamins or other dietary supplements do you take?
• Is there a history of thyroid disease in your family?