Test Code TGMS Thyroglobulin Mass Spectrometry, Serum
Reporting Name
Thyroglobulin, Mass Spec., SUseful For
Accurate measurement of serum thyroglobulin (Tg) in patients with known or suspected antithyroglobulin autoantibodies (TgAb) or heterophile antibodies (HAb)
Reflex testing of samples with previously unknown TgAb status that prove TgAb positive during immunoassay testing
Assisting in the differential diagnosis of early phase silent thyroiditis versus Graves' disease in patients without thyroid cancer (the mass spectrometry-based method would only be required if these patients have TgAb or HAb)
Method Name
Tryptic Protein Fragmentation, purified with Immunocapture, Analysis by Liquid Chromatography Tandem Mass Spectrometry (LC-MS/MS)
(This service is performed pursuant to an agreement with SISCAPA Assay Technologies Inc. covering US Patent 7,632,686)
Performing Laboratory
Mayo Clinic Laboratories in RochesterSpecimen Type
Serum RedSpecimen Required
Collection Container/Tube: Red top (gel tubes/SST are not acceptable)
Submission Container/Tube: Plastic vial
Specimen Volume: 1.25 mL
Collection Instructions: Centrifuge and aliquot serum into a plastic vial.
Specimen Minimum Volume
0.75 mL
Reject Due To
Gross hemolysis | Reject |
Gross lipemia | OK |
Gross icterus | OK |
Specimen Stability Information
Specimen Type | Temperature | Time | Special Container |
---|---|---|---|
Serum Red | Refrigerated (preferred) | 7 days | |
Frozen | 416 days | ||
Ambient | 72 hours |
Reference Values
Healthy individuals with intact, functioning thyroid: ≤33 ng/mL
The reference ranges listed below, however, are for thyroid cancer follow up of athyrotic patients and apply to unstimulated and stimulated thyroglobulin (Tg) measurements. Ranges are based on best practice guidelines and the literature, which includes Mayo Clinic studies, and represent clinical decision levels.
Decision levels for thyroid cancer patients, who are not completely athyrotic (ie, patient has some remnant normal thyroid tissue), have not been established, but are likely to be somewhat higher: remnant normal thyroid tissue contributes to serum Tg concentrations 0.2-1.0 ng/mL per gram of remnant tissue, depending on the thyroid-stimulating hormone (TSH) level.
Tg <0.2 ng/mL: Tg levels must be interpreted in the context of TSH levels, serial Tg measurements, and radioiodine ablation status. Undetectable Tg levels in athyrotic individuals on suppression therapy indicate a minimal risk (<1%-2%) of clinically detectable recurrent papillary/follicular thyroid cancer.
Tg ≥0.2 ng/mL to 2.0 ng/mL: Tg levels must be interpreted in the context of TSH levels, serial Tg measurements, and radioiodine ablation status. Tg levels of 0.2-2.0 ng/mL in athyrotic individuals on suppressive therapy indicate a low risk of clinically detectable recurrent papillary/follicular thyroid cancer.
Tg 2.1 ng/mL to 9.9 ng/mL: Tg levels must be interpreted in the context of TSH levels, serial Tg measurements and radioiodine ablation status. Tg levels of 2.1-9.9 ng/mL in athyrotic individuals on suppression therapy indicate an increased risk of clinically detectable recurrent papillary/follicular thyroid cancer.
Tg ≥10 ng/mL: Tg levels must be interpreted in the context of TSH levels, serial Tg measurements and radioiodine ablation status. Tg levels of 10 ng/mL or above in athyrotic individuals on suppressive therapy indicate a significant (>25%) risk of clinically detectable recurrent papillary/follicular thyroid cancer.
Day(s) Performed
Monday through Friday
CPT Code Information
84432
LOINC Code Information
Test ID | Test Order Name | Order LOINC Value |
---|---|---|
TGMS | Thyroglobulin, Mass Spec., S | 3013-0 |
Result ID | Test Result Name | Result LOINC Value |
---|---|---|
62749 | Thyroglobulin, Mass Spec., S | 3013-0 |
35998 | Interpretation | 59462-2 |
Report Available
3 to 6 daysTest Classification
This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. It has not been cleared or approved by the US Food and Drug Administration.Forms
If not ordering electronically, complete, print, and send an Oncology Test Request (T729) with the specimen.