The Thyroid Binding Globulin (TBG) test measures the level of TBG, a protein that binds thyroid hormones (T4 and T3) in the bloodstream and helps transport them throughout the body. TBG influences how much thyroid hormone is available in bound versus free (active) form.
This test is commonly used to help interpret abnormal total thyroid hormone levels when free hormone levels are normal. Changes in TBG levels can be associated with pregnancy, estrogen therapy, liver disease, genetic factors, or certain medications. TBG testing helps distinguish true thyroid dysfunction from alterations caused by binding protein changes.
Thyroid Binding Globulin
The Thyroid Binding Globulin (TBG) test measures the level of TBG, a protein that binds thyroid hormones (T4 and T3) in the bloodstream and helps transport them throughout the body. TBG influences how much thyroid hormone is available in bound versus free (active) form.
This test is commonly used to help interpret abnormal total thyroid hormone levels when free hormone levels are normal. Changes in TBG levels can be associated with pregnancy, estrogen therapy, liver disease, genetic factors, or certain medications. TBG testing helps distinguish true thyroid dysfunction from alterations caused by binding protein changes.
