Thyroglobulin measurement in the management of patients with differentiated thyroid cancer

The post-operative management of patients with differentiated thyroid carcinoma (DTC) relies on serial measurements of serum thyroglobulin. Current methodologies for thyroglobulin quantitation vary in their analytical and clinical performance. For years, thyroglobulin radioimmunoassays (RIA) and immunometric assays (IMA) have been used despite analytical interferences from anti-thyroglobulin autoantibodies (TgAb) as well as heterophile antibodies (HAb). TgAb interference limits Tg utility as a tumor marker in ∼30% of TgAb-positive patients. Consequently, additional studies are necessary to rule out persistent or recurrent disease in these patients. Recently, thyroglobulin mass spectrometry assays have been introduced as a solution to the interference problems observed in immunoassays. However, their analytical sensitivity is inferior to the high sensitivity immunoassays. The aims of this review are to: (i) review current thyroglobulin assays; (ii) discuss technical limitations of each assay; and (iii) discuss the clinical uses of thyroglobulin in serum and fine-needle aspirate biopsy washouts for the management of DTC patients. An understanding of the technical advantages and disadvantages of Tg assays is critical for clinicians and laboratorians to effectively use and interpret this test in the management of DTC patients.