TBG Thyroxine Binding Globulin
Thyroid blood test TBG (Thyroxine Binding Globulin) serum CLIA method
Your doctor can order a serum test of the TBG level to assess thyroid problems. It can help the doctor diagnose various thyroid disorders, including hypothyroidism and hyperthyroidism.
Symptoms may include:
- constipation
- diarrhea
- Changes in your sleep patterns, such as insomnia, daytime fatigue, or prolonged sleep that is not refreshing
- dry skin
- swollen skin
- Eye problems, such as dryness, irritation, puffiness or bulging
- fatigue
- weakness
- hair loss
- hand tremors
- increased heart rate
- sensitivity to cold
- sensitivity to light
- menstrual irregularity
- weight changes
This test is done to clarify T4 and T3 concentrations that are inconsistent with TSH concentration or in unexplained abnormalities between T4 and FT4,
or greatly increased or decreased T4, or in suspected congenital TBG deficiency.
TBG is elevated in: pregnancy, administration of ovulation inhibitors, phenothiazines, clofibrate, hepatitis
The use of ovulation inhibitors can lead to an increase in thyroxine binding globulin (TBG) in the blood. Ovulation inhibitors often contain hormones, such as estrogen, which can increase levels of TBG. TBG is a protein that binds thyroid hormones, and elevated TBG levels can increase the total amount of bound thyroid hormones in the bloodstream, but this usually does not affect actual thyroid function.
TBG is decreased in: congenital TBG deficiency, protein loss, disorder of protein synthesis, steroid administration.
If the TBG level test indicates that you have an underlying medical problem, consult your doctor to determine the best treatment plan for you. TBG level test is also used to check if a treatment is effective. Tell your doctor about any changes in your health or medication while you are on treatment.
New reference values as of 24-4-23:
0 - 28 days: 443.7 - 722.5 nmol/l
to 1 year 265.2 - 734.4 nmol/l
to 16 years: 249.9 - 617.1 nmol/l
Up to 50 years: 192.1 - 491.3 nmol/l
Up to 120 years: 185.3 - 593.3 nmol/l
