Definitions
  Anaplastic Thyroid Cancer:
A rare type of thyroid cancer that spreads rapidly.

Antithyroid Drugs:
Medications that slow down the thyroid gland's ability to produce thyroid hormone.

Benign:
Non-cancerous.

Beta Blocking Drug:
Medications that help block the symptoms (palpitations, tremor) caused by excess thyroid hormone.

Calcitonin:
A hormone produced by medullary thyroid cancer. Its measurements in the blood is a sensitive test for early diagnosis of this cancer.

Cold Nodule:
A lump in the thyroid gland that does not take up iodine on a scan as well as the surrounding thyroid tissue. Cancers show on a scan as cold nodules but most cold nodules are not cancer.

Compensatory Goiter:
Thyroid enlargement due to inefficient thyroid tissue that compensates for its inefficiency by enlarging.

De Quervain's thyroiditis:
Inflammation of the thyroid gland causing enlargement and pain. It often causes fever and symptoms of hyperthyroidism.

Desiccated Thyroid:
A crude preparation made of animal thyroid glands. It was the first available source of thyroid hormone (thyroxine). Because of poor absorption and impurities it is no longer used.

Diffuse Goiter:
Generalized enlargement of the entire thyroid gland with a smooth surface.

Exophthalmos:
Protrusion of the eyes in Graves' Disease.

Follicular Thyroid Cancer:
A common form of thyroid cancer usually curable by thyroid surgery.

Goiter:
Enlargement of the thyroid gland for any reason. It may be generalized enlargement (diffuse) or asymmetric (nodular).

Graves' Disease:
Hyperthyroidism caused by an overactive diffuse goiter often associated with exophthalmos. Described by Dr. Robert Graves.

Hashimoto's Thyroiditis:
Inflammation of the thyroid gland described by Dr. Hashimoto. Causes a goiter and results in hypothyroidism.

Hormone:
A chemical produced by an endocrine gland and released into the blood. It travels to other organs of the body where it produces its effect.

Hot Nodule:
A lump in the thyroid gland that concentrates iodine on a scan more than the normal surrounding thyroid tissue. Hot nodules are not cancerous.

Hyperthyroidism:
Symptoms of increased metabolism due to excess thyroid hormone in the blood. It may be due to an abnormal thyroid gland or from taking thyroid medication.

Hypothyroidism:
Symptoms of decreased metabolism due to a deficiency of thyroid hormone in the blood.

Inderal:
A beta-blocking drug.

Iodine:
A non-metallic element found in food. It is necessary for normal thyroid function.

Iodine-Induced Goiter:
A goiter caused by excess iodine or by a sensitivity to iodine.

Isthmus:
A small piece of thyroid tissue that connects the right and left lobes of the thyroid gland.

Larynx:
The top of the trachea containing the vocal cords. The "voice box".

Lithium:
A metal, the salt of which is used in treating depression. It sometimes interferes with thyroid function and can cause goiter.

Lugole's Solution:
A liquid medication containing iodine.

Malignant:
Cancerous.

Medullary Thyroid Carcinoma:
A rare form of thyroid cancer that produces an abnormal hormone (calcitonin). This form of thyroid cancer is often hereditary.

Metabolism:
The use of calories and oxygen to produce energy.

Methimazole:
An antithyroid medication.

Multi-Nodular Goiter:
Enlarged thyroid gland with two or more nodules.

Myxedema:
Severe hypothyroidism.

Neoplasm:
A tumor. An abnormal growth. May be benign or malignant.

Nodular Goiter:
Enlarged thyroid gland with one or more nodules.

Nodule:
A lump within the thyroid gland.

Palpitation:
The sensation of the heart beat. It may be too fast, irregular, or just more forceful.

Papillary Thyroid Carcinoma:
A common form of thyroid cancer usually curable by surgery.

Parathyroid Glands:
Four small glands located in the neck, near the thyroid gland. They produce parathormone which controls calcium metabolism. If these glands are damaged or removed at the time of thyroid surgery, serum calcium drops to abnormal levels.

Pituitary Gland:
A small gland the size of a peanut that is located behind the eyes of the base of the brain. It secretes hormones that control other glands (thyroid, adrenal, testicles and ovaries) as well as the kidney and growth.

Propylthiouracil (PTU):
An antithyroid medication.

Radioactive Iodine:
An isotope of iodine used in the diagnosis and treatment of the thyroid.

Scan:
A picture of the thyroid gland.

Silent Thyroiditis:
A self limited thyroiditis that resembles Hashimoto's thyroiditis on biopsy but De Quervain's thyroiditis on scan.

Thyroid Stimulating Hormone (TSH):
A hormone produced by the pituitary that stimulates the thyroid gland. Its measurement is a very sensitive test of thyroid status.

Thyroid Binding Globulin (TBG):
A protein in the blood that binds with thyroxine (T4).

Thyroglobulin:
A protein in the thyroid gland, a small amount of which gets into the blood. Its level is followed after thyroid surgery to detect recurrence of thyroid cancer.

Thyroidectomy:
An operation removing all or part of the thyroid gland.

Thyroiditis:
Inflammation of the thyroid gland.

Thyroxine (T4):
The primary hormone produced by the thyroid gland. It is available as medication.

Toxic Goiter:
An enlarged thyroid gland that produces too much thyroid hormone.

Trachea:
Windpipe.

TRH Test:
A very sensitive test for abnormal thyroid function.

Triiodothyronine (T3):
The second hormone produced by the thyroid gland. It is more potent than thyroxine (T4).

Tumor:
A mass of tissue. It may be benign or malignant.