Thyroxine-Binding Proteins: Blood proteins that bind to THYROID HORMONES such as THYROXINE and transport them throughout the circulatory system.Thyroxine: The major hormone derived from the thyroid gland. Thyroxine is synthesized via the iodination of tyrosines (MONOIODOTYROSINE) and the coupling of iodotyrosines (DIIODOTYROSINE) in the THYROGLOBULIN. Thyroxine is released from thyroglobulin by proteolysis and secreted into the blood. Thyroxine is peripherally deiodinated to form TRIIODOTHYRONINE which exerts a broad spectrum of stimulatory effects on cell metabolism.Thyroxine-Binding Globulin: A thyroid hormone transport protein found in serum. It binds about 75% of circulating THYROXINE and 70% of circulating TRIIODOTHYRONINE.Serum Globulins: All blood proteins except albumin ( = SERUM ALBUMIN, which is not a globulin) and FIBRINOGEN (which is not in the serum). The serum globulins are subdivided into ALPHA-GLOBULINS; BETA-GLOBULINS; and GAMMA-GLOBULINS on the basis of their electrophoretic mobilities. (From Dorland, 28th ed)Norethandrolone: A synthetic hormone with anabolic and androgenic properties and moderate progestational activity.Thyroid Function Tests: Blood tests used to evaluate the functioning of the thyroid gland.Triiodothyronine: A T3 thyroid hormone normally synthesized and secreted by the thyroid gland in much smaller quantities than thyroxine (T4). Most T3 is derived from peripheral monodeiodination of T4 at the 5' position of the outer ring of the iodothyronine nucleus. The hormone finally delivered and used by the tissues is mainly T3.Blood Protein Electrophoresis: Electrophoresis applied to BLOOD PROTEINS.Iodine Isotopes: Stable iodine atoms that have the same atomic number as the element iodine, but differ in atomic weight. I-127 is the only naturally occurring stable iodine isotope.Blood Protein DisordersHypoproteinemia: A condition in which total serum protein level is below the normal range. Hypoproteinemia can be caused by protein malabsorption in the gastrointestinal tract, EDEMA, or PROTEINURIA.Prealbumin: A tetrameric protein, molecular weight between 50,000 and 70,000, consisting of 4 equal chains, and migrating on electrophoresis in 3 fractions more mobile than serum albumin. Its concentration ranges from 7 to 33 per cent in the serum, but levels decrease in liver disease.Alpha-Globulins: Serum proteins that have the most rapid migration during ELECTROPHORESIS. This subgroup of globulins is divided into faster and slower alpha(1)- and alpha(2)-globulins.Hyperthyroidism: Hypersecretion of THYROID HORMONES from the THYROID GLAND. Elevated levels of thyroid hormones increase BASAL METABOLIC RATE.Thyronines: A group of metabolites derived from THYROXINE and TRIIODOTHYRONINE via the peripheral enzymatic removal of iodines from the thyroxine nucleus. Thyronine is the thyroxine nucleus devoid of its four iodine atoms.Hypothyroidism: A syndrome that results from abnormally low secretion of THYROID HORMONES from the THYROID GLAND, leading to a decrease in BASAL METABOLIC RATE. In its most severe form, there is accumulation of MUCOPOLYSACCHARIDES in the SKIN and EDEMA, known as MYXEDEMA.Serum Albumin: A major protein in the BLOOD. It is important in maintaining the colloidal osmotic pressure and transporting large organic molecules.Thyrotropin: A glycoprotein hormone secreted by the adenohypophysis (PITUITARY GLAND, ANTERIOR). Thyrotropin stimulates THYROID GLAND by increasing the iodide transport, synthesis and release of thyroid hormones (THYROXINE and TRIIODOTHYRONINE). Thyrotropin consists of two noncovalently linked subunits, alpha and beta. Within a species, the alpha subunit is common in the pituitary glycoprotein hormones (TSH; LUTEINIZING HORMONE and FSH), but the beta subunit is unique and confers its biological specificity.Dialysis: A process of selective diffusion through a membrane. It is usually used to separate low-molecular-weight solutes which diffuse through the membrane from the colloidal and high-molecular-weight solutes which do not. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)Triiodothyronine, Reverse: A metabolite of THYROXINE, formed by the peripheral enzymatic monodeiodination of T4 at the 5 position of the inner ring of the iodothyronine nucleus.Iodine Radioisotopes: Unstable isotopes of iodine that decay or disintegrate emitting radiation. I atoms with atomic weights 117-139, except I 127, are radioactive iodine isotopes.