Thyroglobulin, Tumor Marker, Serum
Use
Thyroglobulin (Tg) is a thyroid-specific glycoprotein serving as the source for T4 and T3 production. Clinically, it is used in the follow-up of differentiated follicular cell-derived thyroid carcinoma. High levels post-treatment can indicate residual or recurrent disease. Current guidelines consider serum Tg concentrations above 1 ng/mL in an athyrotic individual as suspicious, suggesting additional Tg measurement or imaging may be warranted.
Special Instructions
Patients should not take multivitamins containing biotin for 12 hours prior to specimen collection. All samples are screened for thyroglobulin autoantibodies as their presence can interfere with Tg measurement. TgAb levels less than 1.8 IU/mL are unlikely to cause assay interference.
Limitations
The test can yield misleading results in patients with thyroglobulin autoantibodies (TgAb). Interference can occur due to antibodies against test reagents or when patients have elevated TSH levels. Caution is advised when interpreting results from patients with Tg concentrations above 250,000 ng/mL due to potential assay 'hooking.' Comparative analysis between different methodologies is not advised.
FDA ApprovedNew York Approved
Methodology
Immunoassay (CLIA)
Biomarkers
LOINC Codes
- 57780-9
- 56536-6
- 3013-0
- 69053-7
Result Turnaround Time
1-3 days
Related Documents
For more information, please review the documents below
Specimen
Serum
Volume
1 mL
Minimum Volume
0.5 mL
Container
Red top (serum gel/SST are not acceptable); submission in a Plastic vial
Collection Instructions
Centrifuge and aliquot serum into a plastic vial.
Patient Preparation
For 12 hours before specimen collection, patient should not take multivitamins or dietary supplements (e.g., hair, skin, and nail supplements) containing biotin (vitamin B7).
Causes for Rejection
Gross hemolysis, Gross icterus
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 7 days |
| Refrigerated | 7 days |
| Frozen | 30 days |