Thyroxine Binding Globulin (TBG)

TBG is a protein that carries hormones made by the thyroid gland via the blood to the target tissues. If there is a deficiency of TBG, blood thyroid hormone levels are depleted. TBG has a great binding affinity to thyroid hormones, although there are other carrying proteins such as albumin and transthyretin. In its insufficiency, Total T4 levels decrease, but Free T4 will remain normal. As the bioactive form is sufficient, TBG depletion will not lead to thyroid diseases but give false information about thyroid status, if it is not evaluated together with other thyroid panel parameters (FT4 and TSH).
Interpretation: TBG deficiency is a benign condution. Complications may arise from misinterpretation of T4 levels therefore if treated without taking Free T4 and TSH into consideration, the results will be a mistreatment and worsening of the symptoms of the patient.
Sample: Arm vein blood
Working day: Wednesday (Consult the laboratory)
Result Time: Same day 6:00 PM