Test Directory

This assay is intended for hospitals and laboratories that perform the initial thyroglobulin antibody testing.

Specimen Type: Serum

Collection Container: Gold Top, Serum Separator

Alternate Collection Container: Red Top, Plain

Desired Specimen Volume: 1.5 mL

1. Collect a gold top, separator tube via venipuncture. 

1. Separate serum from cells.
2. Transfer 1.5 mL of serum to a clear aliquot tube (screw cap).

Transport to the laboratory refrigerated.

See patient report.

Any changes in serum Tg concentrations should be interprete in light of the total clinical presentation of the patient, including clinical history, data from additional testing and other appropriate information. Single measurement of thyroglobulin close to the limit of detection is of minimal value in assessing disease status. Serial determinations are required, and should be referenced to the postsurgical baseline Tg result when possible. Evaluation of increasing Tg levels over time are more clinically important.

When a change in Tg method is necessary, it is recommended to re-establish a new baseline Tg level to then interpret further change over time. It should be noted that the thyroid tumors of some patients fail to secret a detectable Tg concentration or may secrete abnormal Tg isoforms that are not detectable by some assays used to measure Tg.

Rare amino sequence mutations with Tg could potentially cause a false-low result in the Tg LC-MS/MS assay, if the sequence variation occurs within the tryptic peptide measured by the assay or eliminates the tryptic cleavage site. In the heterozygote state, the result would be an apparent reduction in Tg concentration by about 50%, while the homozygous state no Tg would be detected.