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HelpOrder Code LAB1408 Thyroxine-Binding Globulin (TBG), Serum
Additional Codes
| Mayo Test ID |
|---|
| TBGI |
Reporting Name
Thyroxine Binding Globulin, SUseful For
Cases in which total thyroid hormone levels do not correlate with the thyrometabolic status, most commonly with pregnancy or the use of contraceptive steroids
Specimen Type
SerumSpecimen Required
Patient Preparation: For 12 hours before specimen collection, do not take multivitamins or dietary supplements containing biotin (vitamin B7), which is commonly found in hair, skin, and nail supplements and multivitamins.
Collection Container/Tube:
Preferred: Red top
Acceptable: Serum gel
Submission Container/Tube: Plastic vial
Specimen Volume: 0.5 mL
Collection Instructions: Centrifuge and aliquot serum into a plastic vial.
Specimen Minimum Volume
0.35 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Serum | Refrigerated (preferred) | 7 days | |
| Frozen | 30 days |
Reject Due To
| Gross hemolysis | Reject |
| Gross lipemia | OK |
Reference Values
Males: 12-26 mcg/mL
Females: 11-27 mcg/mL
For International System of Units (SI) conversion for Reference Values, see www.mayocliniclabs.com/order-tests/si-unit-conversion.html
Performing Laboratory
Mayo Clinic Laboratories in Rochester
Day(s) Performed
Monday, Wednesday, Friday
Method Name
Solid-Phase Chemiluminescent Assay
CPT Code Information
84442
Method Description
The IMMULITE 2000 TBG (thyroxine-binding globulin) is a solid-phase chemiluminescent immunoassay. The solid phase, a polystyrene bead, is coated with a monoclonal antibody specific for TBG. The patient sample and alkaline phosphate-conjugated TBG are added and incubated. During this time, TBG in the sample competes with the enzyme-labeled TBG for a limited number of antibody binding sites on the bead. Unbound enzyme conjugate is removed by washing and the chemiluminescent substrate is added. The substrate, a phosphate ester of adamantyl dixetane, undergoes hydrolysis in the presence of alkaline phosphatase to yield an unstable intermediate. The continuous production of the intermediate results in the sustained emission of light. The photon output is inversely proportional to the concentration of the TBG in the sample.(Package insert: IMMULITE 2000 TBG PIL2KTB-16. Siemens Medical Solutions; 03/15/2018)