A

Addison’s disease/adrenal insufficiency:

a rare, chronic endocrine disorder where the adrenal glands are destroyed by antibodies and do not produce enough steroid hormones (glucocorticoids and often mineralocorticoids).

Adiponectin:

a protein that is produced by fat cells and secreted into the circulation

Agranulocytosis:

a marked decrease in the white blood cell count that causes a patient to be more likely to develop an infection.  This is commonly associated with a fever and/or a sore throat.

Amiodarone induced Thyrotoxicosis:

elevated thyroid hormone levels that can occur as a result of excessive iodine from amiodarone resulting in increased thyroid hormone production and secretion or to destruction of thyroid cells with release of thyroid hormone into the blood

Amiodarone:

an iodine-rich drug that is commonly used for the treatment of irregular heart rhythms.  Amiodarone can cause thyroid problems, including both hypothyroidism and hyperthyroidism.

Anaplastic thyroid cancer: 

a very rare but very aggressive type of thyroid cancer.  In contrast to all other types of thyroid cancer, most patients with anaplastic thyroid cancer die of their cancer and do so within a few years.

Anemia:

low blood count, specifically low levels of red blood cells which carry oxygen around to all of the cells in the body.  Fatigue is a common symptom of anemia.

Antibodies:

proteins that are produced by the body’s immune cells that attack and destroy bacteria and viruses that cause infections.  Occasionally the antibodies get confused and attack the body’s own tissues, causing autoimmune disease.

Atherosclerosis:

“hardening of the arteries”, a condition wherein fatty material (cholesterol, lipids) collects along the inner walls of blood vessels (arteries).  Over time, this material hardens (forms plaques) and can block blood flow through the arteries.   Sometime the plaques can rupture and completely block blood flow through an artery – this is the main cause of heart attacks.

Atypical thyroid biopsy:

this happens when there are some abnormal/atypical cells in the biopsy sample but not enough to diagnose a cancer.  However, because there are abnormal cells in the biopsy sample, the specimen cannot be called benign.  Sometimes a repeat biopsy may be helpful but often surgery is recommended to remove the nodule.

Autoimmune disorders:

A diverse group of disorders that are caused by antibodies that get confused and attack the body’s own tissues.  The disorder depends on what tissue the antibodies attack.  Graves’ disease and Hashimoto’s thyroiditis are examples of autoimmune thyroid disease.  Other Autoimmune disorders include: type 1 diabetes mellitus, Addison’s disease (adrenal insufficiency), vitiligo (loss of pigment of some areas of the skin), systemic lupus erythematosus, pernicious anemia (B12 deficiency), celiac disease, inflammatory bowel disease, myasthenia gravis, multiple sclerosis, and rheumatoid arthritis.

Autoimmune thyroid disease:

a group of disorders that are caused by antibodies that get confused and attack the thyroid.  These antibodies can either turn on the thyroid (Graves’ disease, hyperthyroidism) or turn it off (Hashimoto’s thyroiditis, hypothyroidism).

B

Top

Body Composition:

a group of disorders that are caused by antibodies that get confused and attack the thyroid.  These antibodies can either turn on the thyroid (Graves’ disease, hyperthyroidism) or turn it off (Hashimoto’s thyroiditis, hypothyroidism).

Body-mass index (BMI):

a standardized measure of obesity calculated by dividing the weight in kilograms by the square of the height.  A normal BMI is 18.5-24.9, overweight is 25-30 and obese is >30.

Bone Mineral Density (BMD):  

this is usually measured in the lumbar (lower) spine and the hip and the results give information as to the strength of the bone and the risk of fractures.  The results are expressed as T scores, which as standard deviations from the average bone density in a person in their 20s, when bone mass is the highest.  A T score of -1 to -2.5 is termed Osteopenia and a T score >2.5 is termed Osteoporosis.

BRAF gene:  

this is gene that codes for a protein that is involved in a signaling pathway and is important for cell growth.  Mutations in the BRAF gene in adults appear to cause cancer.

C

Calcitonin:

this is gene that codes for a protein that is involved in a signaling pathway and is important for cell growth.  Mutations in the BRAF gene in adults appear to cause cancer.

Cancer metastasis:

spread of the cancer from the initial organ where it developed to other organs, such as the lungs and bone.

Cancer recurrence:

this occurs when the cancer comes back after an initial treatment that was successful in destroying all detectable cancer at some point.

Cancer-associated genes:

these are genes that are normally expressed in cells.  Cancer cells frequently have mutations in these genes.  It is unclear whether mutations in these genes cause the cancer or are just associated with the cancer cells.  The cancer-associated genes important in thyroid cancer are BRAF, RET/PTC and RAS.

Carcinoembryonic antigen (CEA):

a protein that can be made by certain cancers such as colorectal cancer and medullary thyroid cancer.  CEA may be measured with a blood test.

CAS:

Clinical Activity Score, a scoring system used to evaluate patients with Graves’ ophthalmopathy, and is based on classical signs of inflammation  (pain, redness, swelling and function) and that helps predict which patients will benefit from immunosuppressive treatment

C-cell hyperplasia:

An abnormal growth of parafollicular (C-cells) cells that usually occurs before the development of familial forms of medullary thyroid cancer and is considered a pre-cancerous condition

Celiac disease:

an autoimmune disorder of the small intestine that occurs in genetically predisposed people of all ages from middle infancy onward.

Central hypothyroidism:

a rare cause of hypothyroidism where the thyroid gland is normal and the problem is inadequate TSH secretion from the pituitary gland.

Central neck compartment:

the central portion of the neck between the hyoid bone above, and the sternum and collar bones below and laterally limited by the carotid arteries.

Chemokines:

chemicals produced by lymphocytes that cause inflammation in affected tissues.  One chemokine, CXCL10, has been reported to be elevated in the blood of patients with Hashimotos’s thyroiditis.

Clinical trials:

when a new drug is developed, it must undergo an extensive series of steps, called phases, to prove that it is more effective in patients than the drugs that are currently available to treat the condition.  A Phase I trial tests a new drug or treatment in a small group of people for the first time to evaluate its safety, determine a safe dosage range and identify side effects.  A Phase II trial gives the drug to a larger group of people to see if it is effective and to further evaluate its safety.  A Phase III trial gives the drug to large groups of people to confirm its effectiveness, monitor side effects, compare it to commonly used treatments and collect information that will allow the drug or treatment to be used safely.

Completion thyroidectomy:

surgery to remove the remaining thyroid lobe in thyroid cancer patients who initially had a lobectomy.

Congenital:

Condition that exists at birth.

Congenital:

Condition that exists at birth.

D

Deiodinase enzymes:

Condition that exists at birth.

Desiccated thyroid extract:

thyroid hormone pill made from animal thyroid glands. Currently desiccated thyroid extract is made from pig thyroids and is available as Armour Thyroid^™ and Nature-Throid^™.

Diagnostic Whole Body Scans:

these radioactive iodine scans are performed under TSH stimulation, either after thyroid hormone withdrawal or after injections of recombinant human TSH (Thyrogen), and usually include measuring serum thyroglobulin levels.

Dosimetry:

the calculation of a dose of radiation that will maximize the dose into the remaining cancer while minimizing exposure to other organs and tissues.  It is a time consuming procedure that is usually performed in only specialized situations.  It is often performed by a professional medical dosimetrist with specialized training in the field.

Downs syndrome:

the most common genetic form of mental retardation and the leading cause of certain birth defects and medical conditions

E

Empiric dosing:

this method chooses standard dosing of I-131 based on the treating physician’s decision.  This is the most common method for choosing a dose of I-131  for treating thyroid cancer.

Estrogen:

the main female hormone.  Estrogen levels are increased during pregnancy.

Euthyroid:

a condition where the thyroid gland as working normally and producing normal levels of thyroid hormone.

F

False negative results:

this happens when the thyroid FNAB is consistent with a benign nodule, however, the surgical pathology reveals a malignant thyroid nodule.

False positive results:

this happens when the thyroid FNAB is consistent with a malignant nodule, however, the surgical pathology reveals a benign thyroid nodule.

Familial nonmedullary thyroid cancer:

type of thyroid cancer that runs in families that is not medullary thyroid cancer.  This is usually papillary thyroid cancer and occurs in about 10% of thyroid cancers.

Fetal death:

this occurs when a baby dies later in pregnancy (usually after 22 weeks of pregnancy) before delivery.

Follicular thyroid cancer:

the second most common type of thyroid cancer.

G

Genes:

a molecular unit of heredity of a living organism.   Living beings depend on genes, as they code for all proteins and RNA chains that have functions in a cell. Genes hold the information to build and maintain an organism’s cells and pass genetic traits to offspring.

Genetic hyperthyroidism:

A rare form of hyperthyroidism caused by genetic mutations in the TSH receptor that cause it to be permanently in the “on” position (activating mutations).

Gestational Trophoblastic Disease (GTD):

this occurs with the normal placental tissue grows abnormally into a large mass of grape-like structures called a hydatidiform mole which secretes large amounts of hCG.  In rare cases these high levels of hCG can cause mild hyperthyroidism.

Goiter:

a thyroid gland that is enlarged for any reason is called a goiter.  A goiter can be seen when the thyroid is overactive, underactive or functioning normally.  If there are nodules in the goiter it is called a nodular goiter; if there is more than one nodule it is called a multinodular goiter.

Graves’ disease:

the most common cause of hyperthyroidism in the United States.  It is caused by antibodies that attack the thyroid and turn it on.

Growth Hormone:

secreted by the pituitary, growth hormone works to regulate growth, especially during the growth spurt during childhood.  Growth hormone works through a growth factor call insulin-like growth factor 1 (IGF-1)

H

Hashimoto’s thyroiditis:

the most common cause of hypothyroidism in the United States.  It is caused by antibodies that attack the thyroid and destroy the gland.

hCG:

human chorionic gonadotropin—the major hormone produced by the placenta which is closely related to thyroid stimulating hormone (TSH).  hCG can bind to the TSH receptors present in thyroid tissue and act like a weak form of TSH to cause the thyroid to produce and release more thyroxine and triiodothyronine.  hCG is the hormone measured in the pregnancy tests.

Hemoglobin:

the protein in red blood cells that binds oxygen to carry around to all the cells in the body.  Hemoglobin levels are low with anemia.

Heterophile antibodies:

antibodies directed against foreign proteins that may interfere with hormone assays.  These antibodies often cause hormone measurements that are much higher than the actual levels.

Hyperemesis gravidarum:

a condition during pregnancy in which the woman has severe nausea and continued vomiting that can lead to weight loss, electrolyte imbalance and dehydration.  This usually occurs in the first trimester of pregnancy.

Hyperthyroidism:

a condition where the thyroid gland is overactive and produces too much thyroid hormone.  Hyperthyroidism may be treated with antithyroid meds (Methimazole, Propylthiouracil), radioactive iodine or surgery.

Hypocalcemia:

low calcium levels in the blood, a complication from thyroid  surgery that is usually short-term and relatively easily treated with calcium pills.  If left untreated, low calcium may be associated with muscle twitching or cramping and, if severe, can cause seizures and/or heart problems.

Hypoparathyroidism:

low calcium levels due to decreased secretion of parathyroid hormone (PTH) from the parathyroid glands next to the thyroid.  This can occur as a result of damage to the glands during thyroid surgery and usually resolves.  This may also occur as a result of autoimmune destruction of the glands, in which case it is usually permanent.

Hypothyroidism:

a condition where the thyroid gland is underactive and doesn’t produce enough thyroid hormone.  Treatment requires taking thyroid hormone pills.

Hypopituitarism:

decrease in function of the pituitary gland.  Hypopituitarism can be partial (affecting the secretion of 1 or more hormones) or complete (panhypopituitarism, lack of secretion of all of the pituitary hormones.  The symptoms of hypopituitarism depend on the gland system affected.

Hypothyroidism:

a condition where the thyroid gland is underactive and doesn’t produce enough thyroid hormone.  Treatment requires taking thyroid hormone pills.

I

Immune system:

a system of organs, tissues, and cells in our body that has the role to recognize potentially harmful foreign substances and organisms as well as abnormal body cells and produce antibodies to destroy these factors.

Inadequate/Insufficient biopsy:

this happens with not enough cells are obtained during the biopsy to provide a diagnosis.  This occurs in 5-10% of biopsies.  This often results in the need to repeat the biopsy.

Indeterminate thyroid biopsy:

this happens usually when the diagnosis is a follicular or hurthle cell lesion.  Follicular and hurthle cells are normal cells found in the thyroid.  Current analysis of thyroid biopsy results cannot differentiate between follicular or hurthle cell cancer from noncancerous adenomas.  This occurs in 15-20% of biopsies and often results in the need for surgery to remove the nodule.

Insulin resistance:

a condition where higher amounts of insulin are required to keep blood glucose in the normal range.  This occurs in many patients with diabetes and in individuals at risk for developing diabetes.

In-vitro fertilization:

a procedure when an egg is fertilized outside of the body and then implanted in a woman to achieve a pregnancy

Iodine:

an element found naturally in various foods that is important for making thyroid hormones and for normal thyroid function.  Common foods high in iodine include iodized salt, dairy products, seafood and some breads.

Ionizing radiation: 

radiation that can damage cells, causing cell death or mutation.  It can originate from radioactive materials, x-ray tubes or specialized machines.  It is invisible and not directly detectable by human senses.

L

LDL-C:

low density lipoprotein cholesterol, the type of cholesterol that has been associated with atherosclerosis and heart disease.

Levothyroxine (T4):

the major hormone produced by the thyroid gland and available in pill form as Synthroid™, Levoxyl^™, Tyrosint^™ and generic preparations.

Lipids:

the general term used to describe fat molecules in the blood.  Examples of blood lipids include cholesterol, HDL (“good) cholesterol, LDL (“bad”) cholesterol and triglycerides.

Lobectomy:

surgery to remove one lobe of the thyroid.

Lymph node:

bean-shaped organ that plays a role in removing what the body considers harmful, such as infections and cancer cells.

Lymphocytes:

cells of the immune system that produce antibodies to fight infection

M

Macrocalcifications:

Large flecks of calcium that can be seen either inside a thyroid nodule or in the periphery (so called egg-shell/rim calcifications), usually seen as large bright spots on ultrasonography.

mCi:

millicurie, the units used for I-131.

MEN 2A:

Multiple endocrine neoplasia, type 2A. A hereditary syndrome in which medullary thyroid cancer is often seen in association with other endocrine tumors such as pheochromocytoma (a tumor of the adrenal glands) and hyperparathyroidism (elevated parathyroid hormone levels usually caused by tumors of the parathyroid glands).

Medullary thyroid cancer :

a relatively rare type of thyroid cancer that often runs in families.  Medullary cancer arises from the C-cells in the thyroid.

MCT8:

a protein that is involved with the transport of thyroid hormones from the circulation into the cell there they act by regulating gene expression.

Meta-review: 

a study that combines and analyzes the data from several other studies addressing the same research hypothesis.

Metformin:

a diabetes drug that decreases insulin resistance.

Methimazole:

an antithyroid medication that blocks the thyroid from making thyroid hormone.  Methimazole is used to treat hyperthyroidism, especially when it is caused by Graves’ disease.

Microcalcifications:

Small flecks of calcium within a thyroid nodule, usually seen as small bright spots on ultrasonography. These are frequently seen in nodules containing papillary thyroid cancer.

microRNA: 

a short RNA molecule that has specific actions within a cell to affect the expression of certain genes.

Miscarriage:

this occurs when a baby dies in the first few months of a pregnancy, usually before 22 weeks of pregnancy.

Modified-release recombinant human TSH (MRrhTSH):  

a lower dose of rhTSH that is released more slowly into the blood stream after injection to provide more sustained levels of TSH.

Molecular markers:

genes and microRNAs that are expressed in benign or cancerous cells.  Molecular markers can be used in thyroid biopsy specimens to either to diagnose cancer or to determine that the nodule is benign.

Motesanib:

an anticancer drug that has been shown to be effective in thyroid cancer treatment.

Mutation: 

A permanent change in one of the genes.

Myeloperoxidase antineutrophil cytoplasmic antibody (MPO-ANCA):

specific antibodies that may be induced by drugs which then attack blood vessels.

N

National Cancer Institute (NCI):

a part of the National Institutes of Health in Bethesda, MD, the NCI is the federal government’s primary agency for cancer research and training.

Near-total thyroidectomy:

removal of nearly all of each thyroid lobe, leaving only a small portion of the thyroid gland.

Negative predictive value: 

the likelihood that a patient does not have a disease when the test used to diagnose that disease is negative.

Neonatal death:

this occurs when a baby is born dead or dies in the first 7 days after being born.

Nitrate:

a naturally occurring substance in the diet that prevents iodide from being transported into the thyroid gland where it is used to make the thyroid hormones.  The major sources of nitrate in the diet were found to be lettuce, spinach and broccoli.

Non-diagnostic thyroid biopsy:

this happens when some atypical cells are found but not enough to provide a diagnosis.  This occurs in 5-10% of biopsies.  This often results in the need to repeat the biopsy.

O

Octreotide:

a somatostatin analog drug that usually works to inhibit other hormones.  It is taken as a daily injection into the skin.

Osteonecrosis of the jaw (ONJ):

a condition where decreased blood supply occurs in part of the jaw bone, leading to pain and bone decay. ONJ can occur spontaneously or is associated with steroid use, radiation therapy and bisphosphonate therapy. Risk for ONJ in setting of bisphosphonate use is less than 1 in 100,000 person-years and is dependent on frequency, duration and mode of administration of the drug (intraveneous preparation, higher dose, longer duration are associated with increased risk). Avoidance of dental surgery while on bisphosphonate therapy decreases ONJ risk.

Osteoporosis: 

a decrease in bone mineral density in which the individual is at a significantly increased risk for fractures with little or no trauma or force.  This occurs with a bone mineral density T score of >-2.5.  The areas at highest risk for osteoporotic fractures are the wrist, spine and hip.

Osteopenia: 

a decrease in bone mineral density in which the individual is at a slightly increased risk for fractures with little or no trauma or force.  This occurs with a bone mineral density T score between -1 and -2.5. The areas at highest risk for osteoporotic fractures are the wrist, spine and hip.

Overt Hypothyroidism:

clear hypothyroidism an increased TSH and a decreased T4 level.  All patients with overt hypothyroidism are usually treated with thyroid hormone pills.

P

Papillary microcarcinoma:

clear hypothyroidism an increased TSH and a decreased T4 level.  All patients with overt hypothyroidism are usually treated with thyroid hormone pills.

Papillary thyroid cancer:

the most common type of thyroid cancer.  There are 3 variants of papillary thyroid cancer: classic, follicular and tall-cell.

Parathyroid glands:

usually four small glands located around the thyroid that secrete parathyroid hormone (PTH) which regulates the body’s calcium levels.

Parathyroid hormone (PTH):

the hormone that regulates the body’s calcium levels.  High levels of PTH cause hypercalcemia, or too much calcium in the blood.  Low levels of PTH cause hypocalcemia, or too little calcium in the blood.

Partial thyroidectomy:

surgery that removes only part of the thyroid gland (usually one lobe with or without the isthmus).

Pernicious anemia/B12 deficiency: 

caused by antibodies that destroy the cells in the stomach that produce a protein that is needed for the body to absorb vitamin B12, causing a severe anemia (low blood count).

Pertechnetate thyroid scan: 

pertechnetate is another radioactive substance that is taken up by the thyroid in a similar fashion to iodine and that can be used to image thyroid tissue.

Phytoestrogens: 

a group or compounds naturally found in some plants that have structural similarity to estradiol (the main female sex-hormone), are also called “dietary estrogens and can have some estrogen-like effects.

Pituitary gland:

this endocrine gland sits at the base of the brain and secretes hormones that control thyroid and adrenal function, growth and reproduction.   The pituitary gland secretes TSH to control thyroid function.

Placenta:

A part of the uterus that supplies blood and nutrients to the developing baby during pregnancy.  It forms both a barrier and a connection between the mother and the baby.

Positive predictive value: 

the likelihood that a patient has a disease when the test used to diagnose that disease is positive.

Positron-Emission-Tomography (PET) scans: 

a nuclear medicine imaging test that uses a small amount of radiolabeled glucose to identify cancer.  Since cancer cells are more active than normal cells, the cancer cells take up more of the radiolabeled glucose and show up on the PET scan.  PET scans are frequently combined with CT scans to accurately identify where the cancer is located.

Post- Radioactive iodine Whole Body Scan (post-RAI WBS):

the scan done after radioactive iodine treatment that identifies what was treated and if there is any evidence of metastatic thyroid cancer.

Postpartum thyroiditis:

an inflamation of the thyroid in women who have just delivered a baby. The inflammation first causes mild hyperthyroidism for 1-3 months after delivery.  This is followed by hypothyroidism starting 4-6 months after delivery.  The hypothyroidism resolves and normal thyroid function returns 12-18 months after delivery in most women.   While many women have both the hyperthyroid and the hypothyroid phase, some women may only have one or the other.

Primary hypothyroidism:

the most common cause of hypothyroidism cause by failure of the thyroid grand.

Prophylactic central neck dissection:

careful removal of all lymphoid tissue in the central compartment of the neck, even if no obvious cancer is apparent in these lymph nodes.

Propylthiouracil (PTU):

an antithyroid medication that blocks the thyroid from making thyroid hormone.  Propylthiouracil is used to treat hyperthyroidism, especially in women during pregnancy.

Prospective study: 

a research study in which a group of individuals who have one or more common characteristics are followed over time.

R

Radioactive iodine (RAI):

this plays a valuable role in diagnosing and treating thyroid problems since it is taken up only by the thyroid gland.  I-131 is the destructive form used to destroy thyroid tissue in the treatment of thyroid cancer and with an overactive thyroid.  I-123 is the non-destructive form that does not damage the thyroid and is used in scans to take pictures of the thyroid (Thyroid Scan) or to take pictures of the whole body to look for thyroid cancer (Whole Body Scan).

Radioactive iodine uptake (RAIU):

this is a measurement of activity of the thyroid gland and is reported as the percent of a dose of radioactive iodine that is retained in the thyroid gland 24 h after the dose is given.  An increase in RAIU usually indicates hyperthyroidism.

Recombinant human TSH (rhTSH):

human TSH that is produced in the laboratory and used to produce high levels of TSH in patients after an intramuscular injection.  This is mainly used in thyroid cancer patients before treating with radioactive iodine or performing a whole body scan.  The brand name for rhTSH is Thyrogen^™

RECIST: Response Evaluation Criteria in Solid Tumors –

this is a set of published rules that define when cancer patients improve (“respond”), stay the same (“stable”) or worsen (“progression”) during treatments.

Rituximab:

a selective immunosuppressive drug that is administered intravenously and which is directed against B lymphocytes (cells of the immune system)

S

SEER:

Surveillance, Epidemiology and End Results program, a nation-wide anonymous cancer registry generated by the National Cancer Institute that contains information on 26% of the United States population.  Website: http://seer.cancer.gov/

Selenium:

a mineral found naturally in various foods that is important for making thyroid hormones and for normal thyroid function.  It is needed in small amounts  by the body.

Shear wave elastography:

an ultrasound technique used to measure the stiffness of a thyroid nodule. Cancerous nodules are stiffer than benign nodules.

Sialadenitis:

inflammation of salivary gland.

Sorafenib:

an anticancer drug that has been shown to be effective in thyroid cancer.

Sporadic nonmedullary thyroid cancer:

usual form of thyroid cancer that does not have a genetic component and does not run in families.

Steroids/Glucocorticoids: 

general antiinflammatory and immunosuppressive drugs that are commonly used for the treatment of many autoimmune diseases associated with inflammation

Stimulated thyroglobulin testing:

this test is used to measure whether there is any cancer present in a patient that has previously been treated with surgery and radioactive iodine.  TSH levels are increased, either by withdrawing the patient from thyroid hormone or treating the patient with recombinant human TSH, then levels of thyroglobulin are measured.  Sometimes this test is combined with a whole body iodine scan.

Subclinical Hyperthyroidism:

a mild form of hyperthyroidism where the only abnormal hormone level is a decreased TSH.

Subclinical Hypothyroidism:

a mild form of hypothyroidism where the only abnormal hormone level is an increased TSH.  There is controversy as to whether this should be treated or not.

Suspicious thyroid biopsy: 

this happens when there are atypical cytological features suggestive of, but not diagnostic for malignancy.  Surgical removal of the nodule is required for a definitive diagnosis.

T

Test sensitivity: 

the proportion of patients with a certain disease in whom the test used to diagnose that disease is positive.

Test specificity: 

the proportion of patients without a certain disease in whom the test used to diagnose that disease is negative

Thyroglobulin antibodies:

these are antibodies that attack the thyroid instead of bacteria and viruses, they are a marker for autoimmune thyroid disease, which is the main underlying cause for hypothyroidism and hyperthyroidism in the United States.

Thyroglobulin:

a protein made only by thyroid cells, both normal and cancerous.  When all normal thyroid tissue is destroyed after radioactive iodine therapy in patients with thyroid cancer, thyroglobulin can be used as a thyroid cancer marker in patients that do not have thyroglobulin antibodies.

Thyroglossal duct cyst:

a lump found in the midline of the neck that was part of a structure (thyroglossal duct) that is formed in the development of the thyroid in the fetus.

Thyroid eye disease (TED):  

also known as Graves ophthalmopathy.  TED is most often seen in patients with Graves’ disease but also can be seen with Hashimoto’s thyroiditis.  TED includes inflammation of the eyes, eye muscles and the surrounding tissues.  Symptoms include dry eyes, red eyes, bulging of the eyes and double vision.

Thyroid fine needle aspiration biopsy (FNAB):  

a simple procedure that is done in the doctor’s office to determine if a thyroid nodule is benign (non-cancerous) or cancer.  The doctor uses a very thin needle to withdraw cells from the thyroid nodule.  Patients usually return home or to work after the biopsy without any ill effects.

Thyroid Hemiagenesis:

absence of one lobe of the thyroid at birth

Thyroid hormone receptor genes:

genes that bind thyroid hormone and are responsible for causing all of the actions of thyroid hormone.  There are 2 copies of each thyroid hormone receptor gene, with only one being active ant any one time.

Thyroid hormone therapy:

patients with hypothyroidism are most often treated with Levothyroxine in order to return their thyroid hormone levels to normal.  Replacement therapy means the goal is a TSH in the normal range and is the usual therapy.  Suppressive therapy means that the goal is a TSH below the normal range and is used in thyroid cancer patients to prevent growth of any remaining cancer cells.

Thyroid Hormone Withdrawal (THW):

this is used to produce high levels of TSH in patients by stopping thyroid hormone pills and causing short-term hypothyroidism. This is mainly used in thyroid cancer patients before treating with radioactive iodine or performing a whole body scan.

Thyroid nodule:

an abnormal growth of thyroid cells that forms a lump within the thyroid.  While most thyroid nodules are non-cancerous (Benign), ~5% are cancerous.

Thyroid Remnant Ablation: 

destruction of the small amount of thyroid tissue that remains after surgery (thyroidectomy) with the use of radioactive iodine.

Thyroid scan: 

this imaging test uses a small amount of a radioactive substance, usually radioactive iodine, to obtain a picture of the thyroid gland. A “cold” nodule means that the nodule is not functioning normally. A patient with a “cold” nodule should have a fine needle aspiration biopsy of the nodule. A “functioning”, or “hot”, nodule means that the nodule is taking up radioactive iodine to a degree that is either similar to or greater than the uptake of normal cells. The likelihood of cancer in these nodules is very low and a biopsy is often not needed.

Thyroid stimulating immunoglobulin /TSI:  

antibodies often present in the serum of patients with Graves’ disease that are directed against the TSH receptor, that cause stimulation of this receptor resulting in increased levels of thyroid hormones in the blood and hyperthyroidism

Thyroid Ultrasound:

a common imaging test used to evaluate the structure of the thyroid gland.  Ultrasound uses soundwaves to create a picture of the structure of the thyroid gland and accurately identify and characterize nodules within the thyroid.  Ultrasound is also frequently used to guide the needle into a nodule during a thyroid nodule biopsy.

Thyroidectomy:

surgery to remove the entire thyroid gland.  When the entire thyroid is removed it is termed a total thyroidectomy.  When less is removed, such as in removal of a lobe, it is termed a partial thyroidectomy.

Thyroiditis:

inflammation of the thyroid, most commonly cause by antibodies that attack the thyroid as seen in Hashimoto’s thyroiditis and post-partum thyroiditis.  It can also result from an infection in the thyroid.

Thyrotoxic periodic paralysis (TPP):

attacks of weakness or even whole body paralysis (inability to move) associated with very low levels of potassium in the blood.  TPP is most commonly associated with Graves’ disease.

Thyroxine (T4):

the major hormone produced by the thyroid gland.  T4 gets converted to the active hormone T3 in various tissues in the body.

Total thyroidectomy:

surgery to remove the entire thyroid gland.

Toxic nodular goiter:

characterized by one or more nodules or lumps in the thyroid that may gradually grow and increase their activity so that the total output of thyroid hormone in the blood is greater than normal.

TPO antibodies:

these are antibodies that attack the thyroid instead of bacteria and viruses, they are a marker for autoimmune thyroid disease, which is the main underlying cause for hypothyroidism and hyperthyroidism in the United States.

TRAb:

antibodies often present in the serum of patients with Graves disease that are directed against the TSH receptor, often causing stimulation of this receptor with resulting hyperthyroidism.

Transient hypothyroxinemia: 

temporary decrease in the blood level of thyroxine (T4) after delivery in pre-term infants, followed by the return of normal levels in the absence of any treatment.

Triiodothyronine (T3):

the active thyroid hormone, usually produced from thyroxine.

TSH receptor: 

A molecule (protein) located on the thyroid cell surface that binds TSH and stimulates the production of the thyroid hormones within the thyroid cell.

TSH:  thyroid stimulating hormone –

A molecule (protein) located on the thyroid cell surface that binds TSH and stimulates the production of the thyroid hormones within the thyroid cell.

Type 1 Diabetes:

diabetes caused by antibodies that destroy the insulin producing cells of the pancreas.  Patients with this form of diabetes require insulin to control their blood sugar.

Tyrosine kinases:

proteins that are overactive in many of the pathways that cause cells to be cancerous.

V

Vascular endothelial growth factor receptors (VEGFR):

family of proteins (called tyrosine kinase) that sit on the surface of cells and, in response to other proteins (VEGF), trigger chemical signals to grow new blood vessels and make existing blood vessels bigger. Cancers cannot grow beyond a limited size without blood supply; cancers with working VEGF and VEGFRs are able to grow and spread.

Vitamin D:

a vitamin that is important for maintaining calcium levels by increasing the absorption of calcium from the gut.  Vitamin D is made in our sun after exposure to the sun.

Vasculitis:

a generalized disorder of the immune system where antibodies attack blood vessels and cause inflammation. 

Vitamin D:

a vitamin that is important for maintaining calcium levels by increasing the absorption of calcium from the gut.  Vitamin D is made in our sun after exposure to the sun.

W

Top

White blood cells:

the infection-fighting cells of the blood.

X

Xerostomia:

dry mouth due to lack of saliva, frequently observed after radiation to the head and neck and after I-131 therapy.