Test ID: ZG092
Component(s)- Z0308 Thyroxine Binding Globulin LOINC :3021-3
CPT code: 84442
LOINC:
Specimen Type: Red or SST
Frequency: 1 – 3 days
Instructions: 0.8 mL Serum from Red or SST, Refrigerated. Min 0.5 mL.
Text: Used to distinguish between high T4 levels due to hyperthyroidism and due to increased binding by TBG in euthyroid individuals who have normal levels of free hormones; document cases of hereditary deficiency or increase of TBG; work-up of thyroid disease. TBG is increased by estrogens, tamoxifen, pregnancy, perphenazine, and in some cases of liver disease.
Methodology: Immunochemiluminometric assay (ICMA)