What is HypoThyroidism?

Hypothyroidism, also called underactive thyroid disease, is a common disorder. With hypothyroidism, your thyroid gland does not make enough thyroid hormone.

The thyroid gland is located in the front lower part of your neck. Hormones released by the gland travel through your bloodstream and affect nearly every part of your body, from your heart and brain, to your muscles and skin.

The thyroid controls how your body’s cells use energy from food, a process called metabolism. Among other things, your metabolism affects your body’s temperature, your heartbeat, and how well you burn calories. If you don’t have enough thyroid hormone, your body processes slow down. That means your body makes less energy, and your metabolism becomes sluggish.

What Causes Hypothyroidism?

The most common cause of hypothyroidism is Hashimoto’s thyroiditis. “Thyroiditis” is an inflammation of the thyroid gland. Hashimoto’s thyroiditis is an autoimmune disorder. With Hashimoto’s, your body produces antibodies that attack and destroy the thyroid gland. Thyroiditis may also be caused by a viral infection.

Other causes of hypothyroidism include:

Radiation therapy to the neck area. Treating certain cancers, such as lymphoma, requires radiation to the neck. Radiation damages the cells in the thyroid. This makes it more difficult for the gland to produce hormone.

Radioactive iodine treatment. This treatment is commonly prescribed to people who have an overactive thyroid gland, a condition known as hyperthyroidism. However, radiation destroys the cells in the thyroid gland. This usually leads to hypothyroidism.

What is the thyroid gland?

The thyroid is a butterfly shaped gland that sits low in your neck along the front of the trachea (windpipe). It has two lobes, left and right, and is connected by a band of tissue, called the isthmus. It is responsible for secreting thyroid hormones, which act throughout the body to influence metabolism, growth and development, and body temperature. It is located near several important structures including the superior and recurrent laryngeal nerves (which control the vocal cords) and the parathyroid glands (which regulate the body’s calcium levels).

What is thyroid disease?

Thyroid disease encompasses a large variety of problems with the thyroid. The thyroid can be become underactive (hypothyroid) or overactive (hyperthyroid) for many different reasons. Blood tests are usually the first step in diagnosing thyroid disease. The thyroid can also become enlarged (goiter) or develop nodules (growths within the thyroid). Based on physical exam and blood tests your doctor can determine if other studies are needed such as ultrasound, thyroid scan, or biopsy and the appropriate treatment.

What does the thyroid do?

The thyroid gland uses iodine to produce thyroid hormones — primarily thyroxine (T4) and triiodothyronine (T3). T4 gets converted into T3 (a more active form) in the blood. Thyroid hormones regulate our metabolic rate and affect weight and energy level. The thyroid also produces calcitonin, which contributes to calcium balance. Thyroid hormone production is regulated by a feedback system involving the pituitary gland (a small gland at the base of the brain).

Why do people get thyroid nodules?

The thyroid gland uses iodine to produce thyroid hormones — primarily thyroxine (T4) and triiodothyronine (T3). T4 gets converted into T3 (a more active form) in the blood. Thyroid hormones regulate our metabolic rate and affect weight and energy level. The thyroid also produces calcitonin, which contributes to calcium balance. Thyroid hormone production is regulated by a feedback system involving the pituitary gland (a small gland at the base of the brain).

What should I do if I have a thyroid nodule?

If you feel a thyroid nodule, your doctor will initially start the evaluation by a physical exam and laboratory tests to check if your thyroid function is normal. The next step is usually a thyroid ultrasound. Thyroid ultrasound can help determine the size of the nodule, whether it is solid or fluid filled (cystic), whether there are any other non-palpable nodules, and if there are any suspicious features. Based on the ultrasound and your thyroid function studies it will be decided whether you need a biopsy, known as a fine needle aspiration.

What is a fine needle aspiration biopsy of a thyroid nodule?

If you feel a thyroid nodule, your doctor will initially start the evaluation by a physical exam and laboratory tests to check if your thyroid function is normal. The next step is usually a thyroid ultrasound. Thyroid ultrasound can give us significant information on the nature of thyroid nodules, but frequently a biopsy of the thyroid cells is necessary.

This can often be done in the doctor’s office with a very small needle. It does not require any special preparation and you can return to work and regular activity the same day. Your doctor may use the ultrasound machine and a very thin needle to withdraw cells from the nodule. Usually 3-6 samples must be taken to give the best chance of finding normal or abnormal cells. These cells are reviewed under the microscope by a pathologist and your doctor will then review the results with you

What are the different types of thyroid cancer?

Papillary thyroid cancer (PTC) is the most common type of thyroid cancer making up to 70-80% of all thyroid cancer cases, while Follicular and Hürthle cell cancers represent the second most common. PTC can sometimes spread to the lymph nodes of the neck and those can be surgically removed along with the thyroid.

Follicular or Hurthle cell cancers are more difficult to diagnose on fine needle aspiration (FNA) biopsy compared to PTC and are more likely to spread to the lungs or bones.

Medullary thyroid cancer (MTC) accounts for 3 to 10% of all thyroid cancers and grows from specialized thyroid cells called parafollicular or C-cells that make a hormone called calcitonin. Those with MTC require a total thyroidectomy and central neck dissection, which involves removing the lymph nodes behind the thyroid gland.

Anaplastic thyroid cancer is a rare, but very aggressive cancer, representing only 1-2% of all thyroid cancers, which usually occurs in older patients

Will thyroid hormone help me if I have hypothyroid symptoms but normal thyroid hormone levels?

In several scientific studies, there was no difference between T4 and a placebo (sugar pill) in improving symptoms, depression or well-being in patients with “hypothyroid”
symptoms and normal thyroid hormone levels.

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