Thyroid Binding Globulin – TBG

Our thyroid binding globulin test will help determine the cause of abnormal T4 levels. Thyroid binding globulin does bind T3 in the blood but mainly T4. If large amounts of thyroid binding globulin are present, the body will not have enough free, or usable, T4 to function properly.

Thyroid Binding Globulin is Increased by:

1. estrogens, including birth control pill, premarin and environmental estrogens
2. tamoxifen
3. pregnancy
4. perphenazine
5. liver disease, including hepatitis
6. genetic factors

Thyroid Binding Globulin is Decreased by:

1. chronic liver disease
2. nephrosis (kidney)
3. glucocorticoids
4. androgens/anabolic steroids (e.g. cortisone shots)
5. acromegaly (enlarged tissue due to increased growth hormone)

What’s Being Tested:

• Thyroid Binding Globulin (TBG)

Specimen: Blood(Draw Location | How It Works | FAQs)