Thyroxine Binding Globulin (TBG) details
Description
Thyroxine-binding globulin (TBG) is the main protein responsible for transporting thyroid hormone (T4 and T3) through your bloodstream, with most circulating thyroid hormone bound to it rather than free. Because total T4 and T3 levels are heavily influenced by how much TBG is available (which can shift with pregnancy, estrogen-containing medications, liver disease, or certain genetic conditions), measuring TBG directly can help clarify whether an unusual total T4 or T3 result reflects a true thyroid hormone problem or simply a change in binding protein levels — an important distinction, since free hormone levels (fT4, fT3) are generally more reliable and less affected by TBG changes.
Optimal & Reference range
Thyroxine Binding Globulin (TBG)
µg/mL µg/mL- Low
- Optimal
- Above optimal
- High
- Optimal range
- 13.5 - 23
- Reference range
- 13.5 - 30.9
- Out of range
- <13.5 or >30.9
- Low
- Optimal
- Above optimal
- High
- Optimal range
- 12.7 - 21
- Reference range
- 12.7 - 25.1
- Out of range
- <12.7 or >25.1
Interpretation
- Low: Your result is below the reference range. Discuss it with your healthcare provider, who can interpret it alongside your symptoms and other results.
- Optimal: Your result is within the optimal range.
- Above optimal: Your result is within the reference range, but above the range we consider optimal.
- High: Your result is above the reference range. Discuss it with your healthcare provider, who can interpret it alongside your symptoms and other results.
- Low: Your result is below the reference range. Discuss it with your healthcare provider, who can interpret it alongside your symptoms and other results.
- Optimal: Your result is within the optimal range.
- Above optimal: Your result is within the reference range, but above the range we consider optimal.
- High: Your result is above the reference range. Discuss it with your healthcare provider, who can interpret it alongside your symptoms and other results.
- These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.
Blood tests with Thyroxine Binding Globulin (TBG)
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Single marker
Thyroxine Binding Globulin (TBG)
$24.49
Thyroxine-Binding Globulin (TBG) is a protein that binds and transports thyroid hormones (T3 and T4) in the bloodstream. Measuring TBG helps evaluate thyroid function and can aid in distinguishing between different causes of abnormal thyroid hormone levels.
- Thyroxine Binding Globulin (TBG) The main protein that transports thyroid hormone in your blood. Helps interpret total T4/T3 results, since binding protein levels affect them.