The thyroid is a little, butterfly-shaped gland in the front of your neck. Most of us don’t give it any thought. But the thyroid serves a critical function. It emits hormones that control how your body uses energy. It can affect how energetic you feel and even the pace of your heartbeat.
What is Hypothyroidism?
When your thyroid malfunctions, it can cause an illness called hypothyroidism, or an underactive thyroid. (“Hypo” means less than normal.) Without enough thyroid hormones, many of your body’s functions slow down. You may feel run-down, depressed, and gain weight. During pregnancy, untreated hypothyroidism can harm your baby.
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The thyroid is a butterfly-shaped gland that lies in front of the windpipe (trachea), just below the voice box (larynx). The thyroid gland uses iodine from food to make two thyroid hormones: thyroxine (T4) and triiodothyronine (T3). The thyroid gland stores these hormones and releases them as they are needed.
How Hashimoto’s Disease Causes Hypothyroidism
The most common cause of hypothyroidism in the United States is a condition called Hashimoto’s disease, which affects about 5 percent of the population.
Hashimoto’s disease is an autoimmune disease. That means that your immune system attacks your thyroid. When the thyroid becomes damaged and can’t make enough thyroid hormones, it causes hypothyroidism.
Risk Factors for Hashimoto’s Disease
Researchers aren’t sure why some people get Hashimoto’s disease. Most likely, it’s a combination of genetics and some kind of outside trigger, like a virus. However, some people are more likely to get Hashimoto’s disease than others. Your risk increases if:
- You are a woman: Hashimoto’s disease is eight times more common in women than men.
- You are between 40 and 60 years old: Although the disease may occur in teens or young women, it more often appears between ages 40 and 60.
- Other members of your family have it: Your chance of developing Hashimoto’s disease increases if other family members have the disease.
- You have other autoimmune disorders. These include type 1 diabetes, rheumatoid arthritis, multiple sclerosis, Addison’s disease, and Grave’s disease.
Symptoms and Warning Signs of Hypothyroidism
The hypothyroidism of Hashimoto’s disease is what’s called subclinical. That means it has no symptoms and you may not be aware you have it, particularly in its early stages. But as the hypothyroidism progresses, you may start seeing these symptoms:
- Weight gain.
- Trouble tolerating cold.
- Joint and muscle pain.
- Dry, thinning hair.
- Scant or irregular menstrual periods and problems becoming pregnant.
- Memory problems.
- A slowed heart rate.
The most obvious sign of hypothyroidism is the goiter. That is a visible swelling in the neck, a sign that the thyroid is getting larger as a result of the damage being done to it. The goiter may create tightness or fullness in your throat, but it is usually painless.
Most people with Hashimoto’s disease develop hypothyroidism. That may lead to high cholesterol or heart disease. In rare cases, severe, untreated hypothyroidism may lead to serious issues and be life-threatening. However, that is rare.
Thyroid Hormone Production
The thyroid gland produces two thyroid hormones, triiodothyronine (T3) and thyroxine (T4), and releases them as needed by the body. The hypothalamus and the pituitary gland help control the thyroid gland. The hypothalamus produces thyrotropin-releasing hormone (TRH), which stimulates the pituitary gland to release thyroid-stimulating hormone (TSH). A low level of T3 tells the hypothalamus to release more TRH, and it tells the pituitary to release more TSH. The thyroid gland releases T3 and T4 until the body is receiving the required amount.
Diagnosing Hashimoto’s Disease
Your doctor will order one or more blood tests to find out if you have hypothyroidism. One of the blood tests looks for antithyroid antibodies known as thyroperoxidase antibodies (TPO), which are a sign of Hashimoto’s disease.
In most cases, that’s all you’ll need. However, if your doctor suspects Hashimoto’s disease but you don’t have antibodies in your blood, you may have an ultrasound of your thyroid. The images will show the size of your thyroid and other features of Hashimoto’s disease. The ultrasound also can rule out other causes of an enlarged thyroid.
Treatments for Hashimoto’s Disease
Your treatment will depend on whether Hashimoto’s disease has led to hypothyroidism. If you don’t have hypothyroidism, your doctor may simply monitor your condition.
If you have hypothyroidism, you will be treated with the hormone that your own thyroid can no longer make. You will take levothyroxine, a thyroid hormone medicine. It is identical to the hormone your thyroid makes.
You will need a blood test about six to eight weeks after you start the hormone, and your dosage may be adjusted. Once you’ve reached a dose that works for you, you will probably repeat the blood test in six months and then once a year.
The good news is that your hypothyroidism can usually be completely controlled with hormone medicine. However, you will need to take it for the rest of your life and you shouldn’t stop taking it without talking to your doctor first.
If you suspect you might have a thyroid issue, talk to your primary care provider.
Editor's Note: This article was originally published on , and was last reviewed on .
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