thyroxine-binding globulin

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any of numerous proteins that are insoluble in water or highly concentrated salt solutions but soluble in moderately concentrated salt solutions. All plasma proteins except albumin and prealbumin are globulins. The plasma globulins are separated into five fractions by serum protein electrophoresis (SPE). In order of decreasing electrophoretic mobility these fractions are the alpha1-, alpha2-, beta1-, and beta2-globulins, and the gamma globulins.

The globulins include carrier proteins, which transport specific substances; acute phase reactants, which are involved in the inflammatory process; coagulation factors; complement components; and immunoglobulins. Examples are transferrin, a beta1-globulin that transports iron, and alpha1-antitrypsin, an acute phase reactant that inhibits serum proteases. The gamma globulin fraction is almost entirely composed of immunoglobulins.
accelerator globulin factor V, one of the coagulation factors.
antihemophilic globulin (AHG) factor VIII, one of the coagulation factors.
antilymphocyte globulin (ALG) the gamma globulin fraction of antilymphocyte serum; used as an immunosuppressant in organ transplantation. The term is sometimes used interchangeably with antithymocyte globulin.
antithymocyte globulin (ATG) the gamma globulin fraction of antiserum derived from animals (such as rabbits) that have been immunized against human thymocytes; an immunosuppressive agent that causes specific destruction of T lymphocytes, used in treatment of allograft rejection. The term is sometimes used interchangeably with antilymphocyte globulin.
bacterial polysaccharide immune globulin (BPIG) a human immune globulin derived from the blood plasma of adult human donors immunized with Haemophilus influenzae type b, pneumococcal, and meningococcal polysaccharide vaccines; used for passive immunization of infants under 18 months of age.
cytomegalovirus immune globulin a purified immunoglobulin derived from pooled adult human plasma selected for high titers of antibody against cytomegalovirus; administered intravenously for treatment and prophylaxis of cytomegalovirus disease in transplant recipients.
gamma globulin
hepatitis B immune globulin (HBIG) a specific immune globulin derived from plasma of human donors with high titers of antibodies against hepatitis B surface antigen (HBsAg); used for postexposure prophylaxis following contact with HBsAg-positive materials, also administered to infants of HBsAg-positive mothers.
hyperimmune globulin any of various immune globulin preparations especially high in antibodies against certain specific diseases.
immune globulin
2. a concentrated preparation containing mostly gamma globulins, predominantly IgG, from a large pool of human donors; used for passive immunization against measles, hepatitis A, and varicella and for treatment of hypogammaglobulinemia or agammaglobulinemia in immunodeficient patients, administered intramuscularly. See also immune g. intravenous (human).
immune globulin intravenous (human) a preparation of immune globulin suitable for intravenous administration; used in the treatment of primary immunodeficiency disorders and idiopathic thrombocytopenic purpura, and as an adjunct in the treatment of Kawasaki disease and the prevention of infections associated with chronic lymphocytic leukemia, bone marrow transplantation, and pediatric human immunodeficiency virus infection.
immune human serum globulin immune globulin (def. 2).
immune serum globulin immune g. (def. 2).
pertussis immune globulin a specific immune globulin derived from the blood plasma of human donors immunized with pertussis vaccine; used for the prophylaxis and treatment of pertussis.
rabies immune globulin a specific immune globulin derived from plasma of human donors hyperimmunized with rabies vaccine; administered in conjunction with rabies vaccine in cases of bite or scratch exposure to known or suspected rabid animals.
respiratory syncytial virus immune globulin intravenous a preparation of immunoglobulin G from pooled adult human plasma selected for high titers of antibodies against respiratory syncytial virus; used for passive immunization of infants and young children.
Rh0(D) immune globulin a specific immune globulin derived from human blood plasma containing antibody to the erythrocyte factor Rh0(D); used to prevent Rh-sensitization of Rh-negative females and thus prevent erythroblastosis fetalis in subsequent pregnancies; administered within 72 hours after exposure to Rh-positive blood resulting from delivery of an Rh-positive child, abortion or miscarriage of an Rh-positive fetus, or transfusion of Rh-positive blood. It is also used as a platelet count stimulator in the treatment of idiopathic thrombocytopenic purpura.
serum g's all plasma proteins except albumin, which is not a globulin, and fibrinogen, which is not in the serum. The serum globulins are subdivided into alpha-, beta-, and gamma-globulins on the basis of their relative electrophoretic mobilities.
specific immune globulin a preparation of immune globulin derived from a donor pool preselected for high antibody titer against a specific antigen, such as hepatitis B immune globulin.
tetanus immune globulin a specific immune globulin derived from the blood plasma of human donors who have been immunized with tetanus toxoid; used in the prophylaxis and treatment of tetanus.
thyronine-binding globulin (TBG) (thyroxine-binding globulin) an acidic glycoprotein that is the main binding protein in the blood for thyroxine, and less firmly for triiodothyronine.
vaccinia immune globulin a specific immune globulin derived from the blood plasma of human donors who have been immunized with vaccinia virus smallpox vaccine; used as a passive immunizing agent.
varicella-zoster immune globulin (VZIG) a specific immune globulin derived from plasma of human donors with high titers of varicella-zoster antibodies; used for prevention or amelioration of varicella in immunocompromised patients exposed to the disease and in neonates whose mothers develop varicella in the perinatal period.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.

thy·rox·ine-·bind·ing glob·u·lin (TBG),

an α-globulin of blood with a strong binding affinity for thyroxine; triiodothyronine is bound to it much less firmly; a deficiency or excess of this protein may occur as a rare benign X-linked disorder.
Synonym(s): thyroxine-binding protein (1)
Farlex Partner Medical Dictionary © Farlex 2012

thyroxine-binding globulin

(thī-rŏk′sēn′bīn′dĭng, -sĭn-)
The American Heritage® Medical Dictionary Copyright © 2007, 2004 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved.


A gene on chromosome Xq22.2 that encodes thyroxine-binding globulin (TBG), the major thyroid hormone transport protein, which is genomically—but not functionally—related to the serpin family.
Segen's Medical Dictionary. © 2012 Farlex, Inc. All rights reserved.

thyroxine-binding globulin

TBG An α2-migrating protein that is the main–70% carrrier protein for thyroxine/T4 and triiodothryonine/T3 ↑ in Acute intermittent porphyria, estrogens, hereditary defects, hepatic disease, hypothyroidism, neonates, OCs, perphenazine, pregnancy ↓ in Acromegaly, androgens, hereditary defects, hepatic disease, nephrotic syndrome, phenytoin, prednisone, underlying illness, post-surgery, thyrotoxicosis
McGraw-Hill Concise Dictionary of Modern Medicine. © 2002 by The McGraw-Hill Companies, Inc.
References in periodicals archive ?
Marti, "The allosteric modulation of thyroxine-binding globulin affinity is entropy driven," Biochimica et Biophysica Acta, vol.
[3] Nonstandard abbreviations: [TT.sub.3], total triiodothyronine; BD, Becton-Dickinson; PS, polystyrene; TSH, thyroid-st mulating hormone (thyrotropin); SHBG, sex hormone-binding globulin; [TT.sub.4], total thyroxine; TBG, thyroxine-binding globulin; PBS, phosphate-buffered saline; ALP, alkaline phosphatase; and SDS, sodium dodecyl sulfate.
Reduced clearance rate of thyroxine-binding globulin (TBG) with increased sialylation: a mechanism for estrogen-induced elevation of serum TBG concentration.
From the known equilibrium constants for the three serum binding proteins, thyroxine-binding globulin (TBG), transthyretin, and albumin (5, 6), a maximum of 5% of the protein-bound [T.sub.4] in serum can be dissociated into the free form, but preferably much less than this (7).
Serum thyrotropin response to thyrotropin-releasing hormone and free thyroid hormone indices in patients with familial thyroxine-binding globulin deficiency.
Evidence of inhibition of triiodothyronine binding to thyroxine-binding globulin and thyroxine-binding prealbumin.
Effect of oleate, diphenylhydantoin and heparin on the binding of 1251-thyroxine to purified thyroxine-binding globulin. J Clin Endocrinol Metab 1972;36: 392-4.
Thyroid hormones are transported in serum bound to three proteins: thyroxine-binding globulin (TBG), transthyretin, and albumin.
The concentration of free thyroxine-binding globulin sites (-300 nmol/L) could serve as a buffer against a small release of thyroxine, but these sites could easily be saturated by a large release of the huge R218P HSA-bound reservoir.
If necessary, a T-uptake test or thyroxine-binding globulin measurement can be used to calculate a free-[T.sub.3] index, or a free-[T.sub.3] test can be obtained to clarify an ambiguous increased total-[T.sub.3] result.
There are also ageand pregnancy-related changes in the reference intervals for serum total [T.sub.4], free [T.sub.4], TSH, and thyroxine-binding globulin (14).