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Thyroid Cancer (Thyroglobulin) Monitoring
Test Code90814
CPT Codes
86800
Includes
If Thyroglobulin Antibody is negative, then Thyroglobulin is tested on the Beckman Coulter DxI (CPT code: 84432).
If Thyroglobulin Antibody is positive, then Thyroglobulin is tested by LC/MS/MS (CPT code: 84432).
If Thyroglobulin Antibody is positive, then Thyroglobulin is tested by LC/MS/MS (CPT code: 84432).
Preferred Specimen
3 mL serum
Minimum Volume
1.5 mL
Instructions
Dietary supplements containing biotin may interfere in assays and may skew results to be either falsely high or falsely low. For patients receiving the recommended daily doses of biotin, draw samples at least 8 hours following the last biotin supplementation. For patients on mega-doses of biotin supplements, draw samples at least 72 hours following the last biotin supplementation.
Transport Container
Plastic screw-cap vial
Transport Temperature
Room temperature
Specimen Stability
Room temperature: 6 days
Refrigerated: 7 days
Frozen: 28 days
Refrigerated: 7 days
Frozen: 28 days
Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)
Hemolysis • Lipemia • Plasma • Icteric
Methodology
Immunoenzymatic
Setup Schedule
Set up: Sun, Tues-Sat; Report available: 7-8 days
Reference Range
| Thyroglobulin Antibody | ≤1 IU/mL |
| Thyroglobulin | Athyrotic: <0.1 ng/mL |
| Thyroglobulin, LC/MS/MS | Athyrotic: <0.4 ng/mL |
Clinical Significance
Thyroglobulin measurements are most useful in the postoperative monitoring of patients with papillary, follicular, and Hurthle cell carcinomas. However, approximately 20% of individuals develop autoantibodies to thyroglobulin. Since these antibodies interfere with immunoassay measurement of thyroglobulin, it is necessary to determine the presence or absence of antibodies before measuring thyroglobulin. This panel provides a sensitive method for determination of thyroglobulin autoantibodies, with subsequent measurement of thyroglobulin by either a sensitive immunoassay (Tg Ab negative samples) or LCMSMS (Tg Ab positive samples). The mass spectrometry assay has no interference from autoantibodies.
