Specimens negative for thyroglobulin antibodies (TgAb) are tested for thyroglobulin (Tg) by chemiluminescent immunoassay (CIA) using the Beckman Coulter Access DxI method. Specimens with TgAb results above the upper reference limit are tested for Tg by high-performance liquid chromatography-tandem mass spectrometry (LC-MS/MS). Results obtained with different test methods or kits cannot be used interchangeably. Tg results, regardless of concentration, should not be interpreted as absolute evidence for the presence or absence of papillary or follicular thyroid cancer. Tg testing is not recommended for use as a screening procedure to detect the presence of thyroid cancer in the general population.
Lower limit of detection for Thyroglobulin by LC-MS/MS is 0.5 ng/mL.