Disease: Thyroid Disorders

    What are thyroid disorders?

    Thyroid disorders are conditions that affect the thyroid gland, a butterfly-shaped gland in the front of the neck. The thyroid has important roles to regulate numerous metabolic processes throughout the body. Different types of thyroid disorders affect either its structure or function.

    The thyroid gland is located below the Adam's apple wrapped around the trachea (windpipe). A thin area of tissue in the gland's middle, known as the isthmus, joins the two thyroid lobes on each side. The thyroid uses iodine to produce vital hormones. Thyroxine, also known as T4, is the primary hormone produced by the gland. After delivery via the bloodstream to the body's tissues, a small portion of the T4 released from the gland is converted to triiodothyronine (T3), which is the most active hormone.

    The function of the thyroid gland is regulated by a feedback mechanism involving the brain. When thyroid hormone levels are low, the hypothalamus in the brain produces a hormone known as thyrotropin releasing hormone (TRH) that causes the pituitary gland (located at the base of the brain) to release thyroid stimulating hormone (TSH). TSH stimulates the thyroid gland to release more T4.

    Since the thyroid gland is controlled by the pituitary gland and hypothalamus, disorders of these tissues can also affect thyroid function and cause thyroid problems.

    Picture of the thyroid gland

    What are the specific kinds of thyroid disorders?

    There are specific kinds of thyroid disorders that includes:

    • Hypothyroidism
    • Hyperthyroidism
    • Goiter
    • Thyroid nodules
    • Thyroid cancer

    Hypothyroidism

    Hypothyroidism results from the thyroid gland producing an insufficient amount of thyroid hormone. It can develop from problems within the thyroid gland, pituitary gland, or hypothalamus. Symptoms of hypothyroidism can include:

    • Fatigue
    • Poor concentration or feeling mentally "foggy"
    • Dry skin
    • Constipation
    • Feeling cold
    • Fluid retention
    • Muscle and joint aches
    • Depression
    • Prolonged or excessive menstrual bleeding in women

    Some common causes of hypothyroidism include:

    • Hashimoto's thyroiditis (an autoimmune condition that causes inflammation of the thyroid gland)
    • Thyroid hormone resistance
    • Other types of thyroiditis (inflammation of the thyroid), such as acute thyroiditis and postpartum thyroiditis

    Hyperthyroidism

    Hyperthyroidism describes excessive production of thyroid hormone, a less common condition than hypothyroidism. Symptoms of hypothyroidism usually relate to increased metabolism. In mild cases, there may not be apparent symptoms. Symptoms and signs of hyperthyroidism can include:

    • Tremor
    • Nervousness
    • Fast heart rate
    • Fatigue
    • Intolerance for heat
    • Increase in bowel movements
    • Increased sweating
    • Concentration problems
    • Unintentional weight loss

    Some of the most common causes of hyperthyroidism are:

    • Graves' disease
    • Toxic multinodular goiter
    • Thyroid nodules that overexpress thyroid hormone (known as "hot" nodules)
    • Excessive iodine consumption

    Goiter

    A goiter simply describes enlargement of the thyroid gland, regardless of cause. A goiter is not a specific disease per se. A goiter may be associated with hypothyroidism, hyperthyroidism, or normal thyroid function.

    Thyroid nodules

    Nodules are lumps or abnormal masses within the thyroid. Nodules can be caused by benign cysts, benign tumors, or, less commonly, by cancers of the thyroid. Nodules may be single or multiple and can vary in size. If nodules are excessively large, they may cause symptoms related to compression of nearby structures.

    Thyroid cancer

    Thyroid cancer is far more common among adult women than men or youth. About 2/3 of cases occur in people under age 55. There are different kinds of thyroid cancer, depending upon the specific cell type within the thyroid that has become cancerous. Most cases of thyroid cancer have a good prognosis and high survival rates, especially when diagnosed in its early stages.

    How are thyroid disorders diagnosed?

    In addition to thorough medical history and physical exam, specialized tests are used to diagnose thyroid disorders.

    Blood tests are typically done to measure levels of thyroid hormones and TSH. Blood tests to identify antibodies against thyroid tissue may also be ordered by your doctor, such as titers of anti-thyroglobulin, anti-thyroperoxidase, or TSH receptor stimulating antibodies.

    Imaging tests are commonly used when thyroid nodules or enlargement are present. Ultrasound can visualize the consistency of the tissue within the gland and can often reveal cysts or calcifications. Ultrasound examination cannot distinguish a benign from a malignant process.

    Thyroid scans using radioactive iodine are often performed to evaluate the function of thyroid nodules. The thyroid is the only location in the body that takes up iodine, so when radioactively labeled iodine is given, it is taken up by the thyroid gland. An imaging test typically shows uptake of radioactive iodine by normal thyroid tissue. Areas or nodules that are producing excess hormone (referred to as hyperfunctioning) will show an increased uptake of iodine. These are referred to as "hot" nodules or areas. By contrast, so-called "cold" nodules represent areas with decreased iodine uptake. "Cold" nodules do not produce excess hormone and can sometimes represent cancer.

    Fine needle aspiration and biopsy are techniques that remove a sample of cells or tissue from the thyroid gland for examination and diagnosis by a pathologist, who is a physician trained in the diagnosis of conditions based on tissue samples. Fine needle aspiration (FNA) uses a long, thin needle to withdraw a sample of cells from the thyroid. FNA can be performed in the doctor's office. Sometimes, ultrasound imaging is used to guide the FNA procedure. A biopsy is the surgical sampling of a tissue.

    Hypothyroidism

    Hypothyroidism results from the thyroid gland producing an insufficient amount of thyroid hormone. It can develop from problems within the thyroid gland, pituitary gland, or hypothalamus. Symptoms of hypothyroidism can include:

    • Fatigue
    • Poor concentration or feeling mentally "foggy"
    • Dry skin
    • Constipation
    • Feeling cold
    • Fluid retention
    • Muscle and joint aches
    • Depression
    • Prolonged or excessive menstrual bleeding in women

    Some common causes of hypothyroidism include:

    • Hashimoto's thyroiditis (an autoimmune condition that causes inflammation of the thyroid gland)
    • Thyroid hormone resistance
    • Other types of thyroiditis (inflammation of the thyroid), such as acute thyroiditis and postpartum thyroiditis

    Hyperthyroidism

    Hyperthyroidism describes excessive production of thyroid hormone, a less common condition than hypothyroidism. Symptoms of hypothyroidism usually relate to increased metabolism. In mild cases, there may not be apparent symptoms. Symptoms and signs of hyperthyroidism can include:

    • Tremor
    • Nervousness
    • Fast heart rate
    • Fatigue
    • Intolerance for heat
    • Increase in bowel movements
    • Increased sweating
    • Concentration problems
    • Unintentional weight loss

    Some of the most common causes of hyperthyroidism are:

    • Graves' disease
    • Toxic multinodular goiter
    • Thyroid nodules that overexpress thyroid hormone (known as "hot" nodules)
    • Excessive iodine consumption

    Goiter

    A goiter simply describes enlargement of the thyroid gland, regardless of cause. A goiter is not a specific disease per se. A goiter may be associated with hypothyroidism, hyperthyroidism, or normal thyroid function.

    Thyroid nodules

    Nodules are lumps or abnormal masses within the thyroid. Nodules can be caused by benign cysts, benign tumors, or, less commonly, by cancers of the thyroid. Nodules may be single or multiple and can vary in size. If nodules are excessively large, they may cause symptoms related to compression of nearby structures.

    Thyroid cancer

    Thyroid cancer is far more common among adult women than men or youth. About 2/3 of cases occur in people under age 55. There are different kinds of thyroid cancer, depending upon the specific cell type within the thyroid that has become cancerous. Most cases of thyroid cancer have a good prognosis and high survival rates, especially when diagnosed in its early stages.

    How are thyroid disorders diagnosed?

    In addition to thorough medical history and physical exam, specialized tests are used to diagnose thyroid disorders.

    Blood tests are typically done to measure levels of thyroid hormones and TSH. Blood tests to identify antibodies against thyroid tissue may also be ordered by your doctor, such as titers of anti-thyroglobulin, anti-thyroperoxidase, or TSH receptor stimulating antibodies.

    Imaging tests are commonly used when thyroid nodules or enlargement are present. Ultrasound can visualize the consistency of the tissue within the gland and can often reveal cysts or calcifications. Ultrasound examination cannot distinguish a benign from a malignant process.

    Thyroid scans using radioactive iodine are often performed to evaluate the function of thyroid nodules. The thyroid is the only location in the body that takes up iodine, so when radioactively labeled iodine is given, it is taken up by the thyroid gland. An imaging test typically shows uptake of radioactive iodine by normal thyroid tissue. Areas or nodules that are producing excess hormone (referred to as hyperfunctioning) will show an increased uptake of iodine. These are referred to as "hot" nodules or areas. By contrast, so-called "cold" nodules represent areas with decreased iodine uptake. "Cold" nodules do not produce excess hormone and can sometimes represent cancer.

    Fine needle aspiration and biopsy are techniques that remove a sample of cells or tissue from the thyroid gland for examination and diagnosis by a pathologist, who is a physician trained in the diagnosis of conditions based on tissue samples. Fine needle aspiration (FNA) uses a long, thin needle to withdraw a sample of cells from the thyroid. FNA can be performed in the doctor's office. Sometimes, ultrasound imaging is used to guide the FNA procedure. A biopsy is the surgical sampling of a tissue.

    Source: http://www.rxlist.com

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