Medical Dictionary Definitions A-Z List
Medical Dictionary Definitions A - Z - «T»:
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).
The thyroid gland is located in front of the neck just in f...
Thyroid hormone organification defect IIb
Thyroid hormone organification defect IIb: See Pendred syndrome....
Thyroid hormone receptor
Thyroid hormone receptor: A molecule that receives a thyroid hormone and permits it to dock on the nuclear membrane of a cell. The thyroid hormone receptors (THRs) belong to a family of nuclear receptors that function as hormone-activated transcription factors and act by modulating the expression of...
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
Thyroid insufficiency: See: Hypothyroidism....
Thyroid peroxidase test
Thyroid peroxidase test: A blood test done to detect autoantibodies directed against thyroid peroxidase (TPO), an enzyme in the thyroid gland that is very important to the production of thyroid hormones.
TPO is found in thyroid follicle cells where it catalyzes the iodination of T4 and T3 in the bi...
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:
Thyroid scanning is a nuclear medicine procedure. As the thyroid
gland accumulates radioactive
material (usually, radioactive technetium or iodine), the gland...
Thyroid stimulating hormone
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....
Thyroid stimulating immunoglobulin (TSI)
Thyroid stimulating immunoglobulin (TSI): A form of
immunoglobulin G (IgG) that can bind to thyrotropin (TSH) receptors
on the thyroid gland. TSIs mimic the action of TSH, causing excess
secretion of thyroxine and triiodothyronine. The TSI level is
abnormally high in persons with hyperthyroidism...
Thyroid storm: Thyroid storm
is a severe, life-threatening condition caused by an excess of thyroid hormone. A number of factors can be involved in causing thyroid storm, including over-replacement of thyroid hormones or discontinuing medications taken to treat hyperthyroidism. Symptoms of thyroi...
Thyroidectomy: The surgical removal of part or all of the thyroid gland.
Subtotal thyroidectomy, the more commonly performed operation, involves removal of only a part of the gland. This procedure may be done to:
Remove a tumor from the thyroid,
Reduce the mass of a goitrous (enlarged) thyroid g...
Thyroiditis: Inflammation of the thyroid gland which
is located in front of the neck:
inflamed thyroid gland can release an excess of thyroid hormones into
the blood stream,
resulting in a temporary hyperthyroid state. Once the thyroid gland
is depleted of thyroid
hormones, the patient commo...
Thyroiditis, autoimmune: See: Hashimoto thyroiditis....
Thyroiditis, Hashimoto: See: Hashimoto thyroiditis....
Thyroiditis, postpartum: Postpartum Thyroiditis is an inflammation of the thyroid gland after pregnancy....