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February 10, 2012

Thyroid Blood Tests Glossary of Terms

The following are health and medical definitions of terms that appear in the Thyroid Blood Tests article.

Adam's apple: A familiar anatomic feature in the front of the neck that is due to the forward protrusion of the thyroid cartilage, the largest and most prominent cartilage of the larynx.
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Baseline: 1. Information gathered at the beginning of a study from which variations found in the study are measured.
2. A known value or quantity with which an unknown is compared when measured or assessed.
3. The initial time point in a clinical trial, just before a participant starts to receive the experimental treatment which is being tested. At this reference point, measurable values such as CD4 count are recorded. Safety and efficacy of a drug are often determined by monitoring changes from the baseline values.

Brain: That part of the central nervous system that is located within the cranium (skull). The brain functions as the primary receiver, organizer and distributor of information for the body. It has two (right and left) halves called "hemispheres."

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

Constipation: Infrequent (and frequently incomplete) bowel movements. The opposite of diarrhea, constipation is commonly caused by irritable bowel syndrome, diverticulosis, and medications (constipation can paradoxically be caused by overuse of laxatives). Colon cancer can narrow the colon and thereby cause constipation. The large bowel (colon) can be visualized by barium enema x-rays, sigmoidoscopy, and colonoscopy. Barring a condition such as cancer, high-fiber diets can frequently relieve the constipation.

Contrast: Short for "contrast media." Contrast media are X-ray dyes used to provide contrast, for example, between blood vessels and other tissue.

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

Enlarged thyroid: see goiter.

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."

Fatigue: A condition characterized by a lessened capacity for work and reduced efficiency of accomplishment, usually accompanied by a feeling of weariness and tiredness. Fatigue can be acute and come on suddenly or chronic and persist.
See the entire definition of Fatigue

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

Hypothalamus: The area of the brain that controls body temperature, hunger, and thirst.

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Hypothyroid: Deficiency of thyroid hormone which is normally made by the thyroid gland which is located in the front of the neck:

Iodine: An essential element in the diet used by the thyroid gland to make thyroid hormones.
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Isolate: A group in which mating is always between members of the group. For example, the Amish.

Marker: A piece of DNA that lies on a chromosome so close to a gene that the marker and the gene are inherited together. A marker is thus an identifiable heritable spot on a chromosome. A marker can be an expressed region of DNA (a gene) or a segment of DNA with no known coding function. All that matters is that the marker can be detected and trailed.
See the entire definition of Marker

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.

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.

Pituitary: 1. As an adjective, pertaining to the pituitary gland or its hormonal secretions. 2. As a noun, the pituitary gland itself.
See the entire definition of Pituitary

Pituitary gland: The main endocrine gland. It is a small structure in the head. It is called the master gland because it produces hormones that control other glands and many body functions including growth. The pituitary consists of the anterior and posterior pituitary.
See the entire definition of Pituitary gland

Protein: A large molecule composed of one or more chains of amino acids in a specific order determined by the base sequence of nucleotides in the DNA coding for the protein.
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Recurrence: The return of a sign, symptom or disease after a remission. The reappearance of cancer cells at the same site or in another location is, unfortunately, a familiar form of recurrence.
See the entire definition of Recurrence

Surgery: The word "surgery" has multiple meanings. It is the branch of medicine concerned with diseases and conditions which require or are amenable to operative procedures. Surgery is the work done by a surgeon. By analogy, the work of an editor wielding his pen as a scalpel is s form of surgery. A surgery in England (and some other countries) is a physician's or dentist's office.
See the entire definition of Surgery

Sweating: The act of secreting fluid from the skin by the sweat (sudoriferous) glands. These are small tubular glands situated within and under the skin (in the subcutaneous tissue). They discharge by tiny openings in the surface of the skin.
See the entire definition of Sweating

Thyroglobulin: A protein found in the thyroid gland. Some thyroglobulin can be found in the blood, and this amount may be measured after thyroid surgery to determine whether thyroid cancer has recurred. Thyroglobulin derived from pig thyroid glands is sometimes given to treat thyroid dysfunction. Abbreviated Tg.

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.)
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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.


See the entire definition of Thyroid cancer

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 hormones: Chemical substances made by the thyroid gland, which is located in the front of the neck. This gland uses iodine to make thyroid hormones, which are essential for the function of every cell in the body. They help regulate growth and the rate of chemical reactions (metabolism), and are involved in the circadian rhythms that govern sleep, among other essential functions.
See the entire definition of Thyroid hormones

Thyroid stimulating hormone: A hormone produced by the pituitary gland at the base of the brain in response to signals from the hypothalamus gland in the brain. Thyroid stimulating hormone (TSH) promotes the growth of the thyroid gland in the neck and stimulates it to produce more thyroid hormones. When there is an excessive amount of thyroid hormones, the pituitary gland stops producing TSH, reducing thyroid hormone production. This mechanism maintains a relatively constant level of thyroid hormones circulating in the blood.
See the entire definition of Thyroid stimulating hormone

Thyroidectomy: The surgical removal of part or all of the thyroid gland.


See the entire definition of Thyroidectomy

Thyrotropin: A hormone produced by the pituitary gland at the base of the brain in response to signals from the hypothalamus gland in the brain.
See the entire definition of Thyrotropin

Thyroxine: Abbreviated T4. A hormone made by the thyroid gland that has four iodine molecules attached to its molecular structure. T4 and other thyroid hormones help regulate growth and control the rate of chemical reactions (metabolism) in the body.

Trachea: A tube-like portion of the breathing or "respiratory" tract that connects the "voice box" (larynx) with the bronchial parts of the lungs.


See the entire definition of Trachea

Triiodothyronine: A hormone made by the thyroid gland. It has three iodine molecules attached to its molecular structure. It is the most powerful thyroid hormone, and affects almost every process in the body, including body temperature, growth, and heart rate.
See the entire definition of Triiodothyronine

TSH: Stands for thyroid stimulating hormone, a hormone produced by the pituitary gland at the base of the brain in response to signals from the hypothalamus gland in the brain. TSH promotes the growth of the thyroid gland in the neck and stimulates it to produce more thyroid hormones. When there is an excessive amount of thyroid hormones, the pituitary gland stops producing TSH, reducing thyroid hormone production. This mechanism maintains a relatively constant level of thyroid hormones circulating in the blood.
See the entire definition of TSH

Tumor: An abnormal mass of tissue. Tumors are a classic sign of inflammation, and can be benign or malignant (cancerous). There are dozens of different types of tumors. Their names usually reflect the kind of tissue they arise in, and may also tell you something about their shape or how they grow. For example, a medulloblastoma is a tumor that arises from embryonic cells (a blastoma) in the inner part of the brain (the medulla). Diagnosis depends on the type and location of the tumor. Tumor marker tests and imaging may be used; some tumors can be seen (for example, tumors on the exterior of the skin) or felt (palpated with the hands).
See the entire definition of Tumor

Tumor marker: Tumor markers are substances that can be detected in higher-than-normal amounts in the blood, urine, or body tissues of some patients with certain types of cancer. A tumor marker may be made by a tumor itself or by the body in response to the tumor. Such a substance serves to "mark" the tumor; it is a "tumor marker."
See the entire definition of Tumor marker

Ultrasound: High-frequency sound waves. Ultrasound waves can be bounced off of tissues using special devices. The echoes are then converted into a picture called a sonogram. Ultrasound imaging, referred to as ultrasonography, allows physicians and patients to get an inside view of soft tissues and body cavities, without using invasive techniques. Ultrasound is often used to examine a fetus during pregnancy. There is no convincing evidence for any danger from ultrasound during pregnancy.

Windpipe: The trachea, a tube-like portion of the respiratory (breathing) tract that connects the larynx (the voicebox) with the bronchial parts of the lungs.


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  • Related Diseases & Conditions

    • Hypothyroidism
      • 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.
    • Dizziness
      • Dizziness is a symptom that is often applies to a variety of sensations including lightheadedness and vertigo. Causes of dizziness include low blood pressure, heart problems, anemia, dehydration, and more. Treatment of dizziness depends on the cause.
    • Muscle Spasms
      • Muscle spasms are involuntary muscle contractions that come on suddenly and are usually quite painful. Dehydration, doing strenuous exercise in a hot environment, prolonged muscle use, and certain diseases of the nervous system may cause muscle spasms. Symptoms and signs of a muscle spasm include an acute onset of pain and a possible bulge seen or felt beneath the skin where the muscle is located. Gently stretching the muscle usually resolves a muscle spasm.
    • Hyperthyroidism
      • 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.
    • Fibromyalgia
      • Fibromyalgia, formerly known as fibrositis, causes chronic pain, stiffness, and tenderness of muscles, tendons, and joints without detectable inflammation. Fibromyalgia patients have an unusually low pain threshold. Symptoms of fibromyalgia include fatigue, abnormal sleep, mental/emotional disturbances, abdominal pain, migraine and tension headaches, and irritable bladder. Treatment of fibromyalgia involves patient education, medication, exercise, and stress reduction.
    • Thyroid Cancer
      • 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.
    • Fainting (Syncope)
      • Fainting, also referred to as blacking out, syncope, or temporary loss of consciousness has many causes. Often a person will have signs or symptoms prior to the fainting episode. Diagnosis and treatment depends upon the cause of the fainting or syncope episode.
    • Hair Loss
      • There are many causes of scalp hair loss. This featured article covers the common ones such as patchy hair loss (alopecia areata, trichotillomania, and tinea capitis), telogen effluvium, and androgenetic alopecia (male-pattern baldness, female-pattern baldness).
    • Hashimoto's Thyroiditis
      • 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
      • 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.
    • Thyroid Disease
      • 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.
    • Fatigue
      • Fatigue can be described in various ways. Sometimes fatigue is described as feeling a lack of energy and motivation (both mental and physical). The causes of fatigue are generally related to a variety of conditions or diseases for example, anemia, mono, medications, sleep problems, cancer, anxiety, heart disease, drug abuse, and more. Treatment of fatigue is generally directed toward the condition or disease that is causing the fatigue.
    • Graves' 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.
    • Myxedema Coma
      • Myxedema coma is the loss of brain function due to severe longstanding low levels of thyroid hormone in the blood. Myxedema coma is a life-threatening complication of hypothyroidism. Examples of triggers of myxedema coma include medications, infections stroke, trauma and more. Some of the ymptoms of myxedema coma include: hypothermia, seizures, coma, difficulty breathing and more. Treatment of myxedema coma depend on the severity of the condition.
    • Thyroiditis
      • 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.
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Thyroid Blood Tests

What is the thyroid gland?

The thyroid is a gland that makes and stores essential hormones that help regulate the heart rate, blood pressure, body temperature, and the rate of chemical reactions (metabolism) in the body. It is located in the anterior neck just below the Adams apple.

The thyroid gland is the, is the main part of the body that takes up iodine. In a thyroid scan, iodine is labeled with a radioactive tracer, and a special camera is used to measure how much tracer is absorbed from the bloodstream by the thyroid gland. If a patient is allergic to iodine, technetium can be used as an alternative.

How is the thyroid scan performed?

A thyroid scan is an outpatient procedure usually done in the nuclear medicine section of a hospital. This is usually part of the radiology department.

If you have a thyroid scan, you will be asked to take a drink, or swallow a pill containing the...

Read the Thyroid Scan article »







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