Thyroid binding globulin (TBG)

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  • Thyroid Binding Globulin (TBG) (measured by electrophoresis)
  • Thyroid Binding Globulin (TBG) (measured by radioimmunoassay)

Analyzer Report

Disclaimer: THIS TOOL DOES NOT PROVIDE MEDICAL ADVICE. It is intended for informational purposes only and is not a substitute for professional medical consultation, diagnosis, or treatment.

Frequently Asked Questions

What does the TBG count indicate?

In the circulation, thyroid hormones such as thyroxine (T4) and triiodothyronine (T3) are bound to a protein called thyroid binding globulin (TBG), which is generated in the liver. TBG’s principal role is to carry thyroid hormones to their target tissues. The measurement of TBG count can be helpful in evaluating thyroid function.

What does a low TBG count show?

Low TBG levels may indicate the following:

  • Liver disease: Liver dysfunction or injury can result in decreased TBG synthesis, which in turn reduces TBG levels in the blood.
  • High quantities of androgen hormones, as in androgen treatment, can inhibit TBG synthesis and thereby reduce TBG levels.
What does a high TBG count show?

An elevated TBG level could indicate:

  • Increased TBG levels can result from inherited genetic variants that induce a disorder called familial dysalbuminemic hyperthyroxinemia (FDH).
  • Hormonal shifts occur during pregnancy, causing TBG levels to increase.
  • Contraceptives and estrogen therapy: Estrogen can stimulate TBG synthesis, leading to elevated blood levels of this hormone.

Blood proteins called thyroid-binding globulin (TBG) bind thyroid hormones such thyroxine (T4) and triiodothyronine (T3). It’s a key factor in how these hormones get distributed throughout the body.

TBG count is a quantification of TBG levels in the blood. Several factors, such as heredity, hormones, liver function, drugs, and health conditions, might influence TBG levels.

Thyroid hormone total blood levels can be affected by abnormal TBG levels even when free or unbound hormone levels are normal. Total thyroid hormone levels may rise with elevated TBG and fall with decreased TBG.


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