The following are health and medical definitions of terms that appear in the Thyroid Scan article.
Allergy: A misguided reaction to foreign substances by the immune system, the body system of defense against foreign invaders, particularly pathogens (the agents of infection). The allergic reaction is misguided in that these foreign substances are usually harmless. The substances that trigger allergy are called allergen. Examples include pollens, dust mite, molds, danders, and certain foods. People prone to allergies are said to be allergic or atopic. See the entire definition of Allergy
Anterior: The front, as opposed to the posterior. The anterior surface of the heart is toward the breast bone (the sternum). See the entire definition of Anterior
Aspiration: Removal of a sample of fluid and cells through a needle. Aspiration also refers to the accidental sucking in of food particles or fluids into the lungs.
Biopsy: The removal of a sample of tissue for purposes of diagnosis. (Many definitions of "biopsy" stipulate that the sample of tissue is removed for examination under a microscope. This may or may not be the case. The diagnosis may be achieved by other means such as by analysis of chromosomes or genes.) See the entire definition of Biopsy
Blood pressure: The blood pressure is the pressure of the blood within the arteries. It is produced primarily by the contraction of the heart muscle. It's measurement is recorded by two numbers. The first (systolic pressure) is measured after the heart contracts and is highest. The second (diastolic pressure) is measured before the heart contracts and lowest. A blood pressure cuff is used to measure the pressure. Elevation of blood pressure is called "hypertension".
Cancer: An abnormal growth of cells which tend to proliferate in an uncontrolled way and, in some cases, to metastasize (spread). See the entire definition of Cancer
Diagnosis:1 The nature of a disease; the identification of an illness. 2 A conclusion or decision reached by diagnosis. The diagnosis is rabies. 3 The identification of any problem. The diagnosis was a plugged IV. See the entire definition of Diagnosis
Essential:1. Something that cannot be done without. 2. Required in the diet, because the body cannot make it. As in an essential amino acid or an essential fatty acid. 3. Idiopathic. As in essential hypertension. "Essential" is a hallowed term meaning "We don't know the cause."
Gland:1. A group of cells that secrete a substance for use in the body. For example, the thyroid gland. 2. A group of cells that removes materials from the circulation. For example, a lymph gland.
Heart: The muscle that pumps blood received from veins into arteries throughout the body. It is positioned in the chest behind the sternum (breastbone; in front of the trachea, esophagus, and aorta; and above the diaphragm muscle that separates the chest and abdominal cavities. The normal heart is about the size of a closed fist, and weighs about 10.5 ounces. It is cone-shaped, with the point of the cone pointing down to the left. Two-thirds of the heart lies in the left side of the chest with the balance in the right chest. See the entire definition of Heart
Heart rate: The number of heart beats per unit time, usually per minute. The heart rate is based on the number of contractions of the ventricles (the lower chambers of the heart). The heart rate may be too fast (tachycardia) or too slow (bradycardia). The pulse is bulge of an artery from the wave of blood coursing through the blood vessel as a result of the heart beat. The pulse is often taken at the wrist to estimate the heart rate.
Hormone: A chemical substance produced in the body that controls and regulates the activity of certain cells or organs. See the entire definition of Hormone
Inflammation: A basic way in which the body reacts to infection, irritation or other injury, the key feature being redness, warmth, swelling and pain. Inflammation is now recognized as a type of nonspecific immune response. See the entire definition of Inflammation
Iodine: An essential element in the diet used by the thyroid gland to make thyroid hormones. See the entire definition of Iodine
Metabolism: The whole range of biochemical processes that occur within an organism. Metabolism consists both of anabolism and catabolism (the buildup and breakdown of substances, respectively). The biochemical reactions are known as metabolic pathways and involve enzymes that transform one substance into another substance, either breaking down a substance or building a new chemical substance. The term is commonly used to refer specifically to the breakdown of food and its transformation into energy.
Neck: The part of the body joining the head to the shoulders. Also, any narrow or constricted part of a bone or organ that joins its parts as, for example, the neck of the femur bone.
Nodule: A small solid collection of tissue, a nodule is palpable (can be felt). It may range in size from greater than 1.0 cm (3/8 inch) to somewhat less than 2 cm (13/16 inch) in diameter. A nodule may be present in the epidermis, dermis or subcutis (at any level in the skin). See the entire definition of Nodule
Nuclear medicine: The branch of medicine concerned with the use of radioisotopes in the diagnosis, management, and treatment of disease. Nuclear medicine uses small amounts of radioactive materials or radiopharmaceuticals, substances that are attracted to specific organs, bones, or tissues. The radiopharmaceuticals used in nuclear medicine emit gamma rays that can be detected externally by special types of cameras: gamma or PET cameras. These cameras work in conjunction with computers used to form images that provide data and information about the area of body being imaged. The amount of radiation from a nuclear medicine procedure is comparable to that received during a diagnostic x-ray.
Outpatient: A patient who is not an inpatient (not hospitalized) but instead is cared for elsewhere -- as in a doctor's office, clinic, or day surgery center. The term outpatient dates back at least to 1715. Outpatient care today is also called ambulatory care.
Radioactive: Emitting energy waves due to decaying atomic nuclei. Radioactive substances are used in medicine as tracers for diagnosis, and in treatment to kill cancerous cells.
Radioactive iodine: An isotope of the chemical element iodine that is radioactive. Radioactive iodine is used in diagnostic tests as well as in radiotherapy of an hyperactive thyroid gland (hyperthyroidism), most often due to Graves' disease. See the entire definition of Radioactive iodine
Radioactive tracer: A radioactive molecule that can be sent through the body's circulatory or urinary system, with its progress followed by a radiation-sensitive machine.
Radiology: The branch of medicine that uses ionizing and nonionizing radiation for the diagnosis and treatment of disease. See the entire definition of Radiology
Scan: As a noun, the data or image obtained from the examination of organs or regions of the body by gathering information with a sensing device. See the entire definition of Scan
Thyroid:1. The thyroid gland. Also, pertaining to the thyroid gland. 2. A preparation of the thyroid gland used to treat hypothyroidism. 3. Shaped like a shield. (The thyroid gland was so-named by Thomas Wharton in 1656 because it was shaped like an ancient Greek shield.) See the entire definition of Thyroid
Thyroid cancer: Cancer of the gland in front of the neck that normally produces thyroid hormone which is important to the normal regulation of the metabolism of the body. There are 4 major types of thyroid cancer -- papillary, follicular, medullary, and anaplastic. The most common symptom of thyroid cancer is a lump, or nodule, that can be felt in the neck. The only certain way to tell whether a thyroid lump is cancer is by examining the thyroid tissue, obtained using a needle or surgery to obtain a biopsy.
Thyroid gland: A gland that makes and stores hormones that help regulate the heart rate, blood pressure, body temperature, and the rate at which food is converted into energy. Thyroid hormones are essential for the function of every cell in the body. They help regulate growth and the rate of chemical reactions (metabolism) in the body. Thyroid hormones also help children grow and develop. See the entire definition of Thyroid gland
Thyroid hormone: A chemical substance made by the thyroid gland for export into the bloodstream. The thyroid gland needs iodine to make thyroid hormones. The two most important thyroid hormones are thyroxine (T4) and triiodothyronine (T3). See the entire definition of Thyroid hormone
Thyroid scan: An image taken of the thyroid gland after radioactive iodine is taken by mouth. The thyroid gland is in front of the neck:
Urine: Liquid waste. The urine is a clear, transparent fluid. It normally has an amber color. The average amount of urine excreted in 24 hours is from 40 to 60 ounces (about 1,200 cubic centimeters). Chemically, the urine is mainly an aqueous (watery) solution of salt (sodium chloride) and substances called urea and uric acid. Normally, it contains about 960 parts of water to 40 parts of solid matter. Abnormally, it may contain sugar (in diabetes), albumen (a protein) (as in some forms of kidney disease), bile pigments (as in jaundice), or abnormal quantities of one or another of its normal components.
Hypothyroidism is any state in which thyroid hormone production is below normal. Normally, the
rate of thyroid hormone production is controlled by the brain at the pituitary.
Hypothyroidism is a very common condition and the symptoms of hypothyroidism are
often subtle.
Hyperthyroidism is an excess of thyroid hormone resulting from an overactive thyroid gland. Symptoms can include increased heart rate, weight
loss, depression, and cognitive slowing. Treatment is by medication, the use of
radioactive iodine, thyroid surgery, or reducing the dose of thyroid hormone.
There are four major types of thyroid cancer: papillary, follicular, medullary, and anaplastic thyroid cancer. Tumors on the thyroid are referred to as thyroid nodules. Symptoms of thyroid cancer include swollen lymph nodes, pain in the throat, difficulty swallowing, hoarseness, and a lump near the Adam's apple. Treatment usually involves chemotherapy, surgery, radioactive iodine, hormone treatment or external radiation and depends upon the type of thyroid cancer, the patient's age, the tumor size, and whether the cancer has metastasized.
Hashimoto's thyroiditis is the most common cause of hypothyroidism in the US. This conditions is caused by inflammation of the thyroid gland. Symptoms may include: fatigue, weight gain, cold intolerance, excessive sleepiness, dry or coarse hair, difficulty swallowing, a lump in the front of the throat, and many more. Treatment is usually hypothyroid medication.
Thyroid nodules are the most common endocrine problem in the United States. The term "thyroid nodule" refers to any abnormal growth that forms a lump in the thyroid gland. The vast majority of thyroid nodules are benign.
There are many types of thyroid disease. Some occur due to the function of the thyroid itself such as hypothyroidism, hyperthyroidism, Hashimoto's thyroiditis, etc. Some causes of thyroid disease occur due to problems with the structure of the thyroid gland such as goiters, thyroid nodules, and thyroid cancer. Treatment of thyroid disease depends on the cause of the disease.
Graves' disease is an autoimmune disease that affects the thyroid. Some of the symptoms of Graves' disease include hand tremors, rapid heartbeat, trouble sleeping, enlarged thyroid, thinning of the skin or fine brittle hair. Causes of Graves' disease are thought to be multifactorial such as genes, gender, stress, and infection. Treatment for Graves' disease is generally medication.
Thyroiditis is the inflammation of the thyroid gland. The inflamed thyroid gland can release an excess of thyroid hormones into the blood stream, resulting in a temporary hyperthyroid state. Some forms of thyroiditis can be diagnosed based on tenderness and enlargement of the thyroid gland. A thyroid scan sometimes is used in making the diagnosis. Thyroiditis can also be diagnosed with a biopsy of the thyroid gland.
When I was asked to write an article on "thyroid disease", I took a very deep
breath. The task seemed daunting. As any Endocrinologist (hormone specialist)
knows, there are many subtopics within this giant topic, and an article like
this could go on for a hundred pages! So, once I caught my breath, I decided to
simply design this article to present a "rough guide" to the thyroid. This
article will be an outline or introduction to many conditions that involve the
thyroid gland. As you read through this, you will find a number of links that
will take you to more in-depth articles dealing with the specific topic in
question.
Thyroid 101: What is the thyroid and what does it do?
The thyroid is a butterfly-shaped gland located in the
front of the neck just
below the Adams apple. The gland wraps around the windpipe (trachea) and has a
shape that is similar to a butterfly ...
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