Thyroxine-binding globulin (TBG) is a globulin protein encoded by the SERPINA7 gene in humans. TBG binds thyroid hormones in circulation. It is one of three transport proteins (along with transthyretin and serum albumin) responsible for carrying the thyroid hormones thyroxine (T 4) and triiodothyronine (T 3) in the bloodstream.

Screening for interference in thyroid hormone (T4 and T3) and/or thyrotropin (TSH) laboratory assays should be considered in any patient with apparently anomalous or discordant TFTs.

Jul 4, 2023 · Confirmatory testing with TBG, free T4, and TSH help rule out congenital hypothyroidism and rule in the diagnosis of TBG deficiency. Thyroxine-binding globulin has been found to be present in the serum of a fetus as early as at 12 weeks gestation.

Jul 1, 2024 · The serum TBG level test is a blood test—sometimes referred to as the thyroxine-binding globulin test—that measures the amount of the TBG protein in your blood. Thyroid hormone that isn't bound to TBG is called "free" T3 or T4.

Dec 2, 2024 · Thyroid hormone-binding globulin (TBG) is a protein produced in the liver that binds T3 and T4. When TBG binds thyroid hormones, it does so reversibly. Elevated levels of TBG may lead to increased total T4 and total T3, but not usually a change in thyroid function.[12]

Free T3 and T4 are then released into the bloodstream, where they are bound to serum proteins for transport. The primary transport protein is thyroxine-binding globulin (TBG), which has high affinity but low capacity for T3 and T4. TBG normally …

Thyroxine binding globulin (TBG) is the high-affinity serum binding protein for thyroxine and triiodothyronine. Normally, the thyroid adjusts to changing concentrations of TBG by producing more, or less, thyroid hormone to maintain a constant level of …

Jul 4, 2023 · While there are higher amounts of albumin in serum, TBG has a greater affinity to thyroxine (T4). Abnormalities in the functionality and amount of TBG can cause variations in the total amount of T4 in the serum, but not in the amount of bioactive free T4.

Dec 17, 2024 · Thyroxine-binding globulin and thyroid-binding globulin are the same. Thyroxine-binding globulin is the protein that binds with thyroxine, specifically to T4 and, to a lesser extent, T3. Thyroxine-binding globulin carries thyroid hormones (Thyroxine T4 and Triiodothyronine T3) to various body parts.

Thyroxine-binding globulin (TBG) is the main transport protein for thyroid hormones in the circulation. Approximately 75% of circulating T4 is bound to TBG and the rest is bound to transthyretin and/or albumin and a very small fraction (less …