title: Antithyroglobulin antibodies in patients with differentiated thyroid carcinoma: methods of detection, interference with serum thyroglobulin measurement and clinical significance.
abstract: Antithyroglobulin antibodies (TgAb) were measured using a chemiluminescent immunoassay (ICMA) and an agglutination test. TgAb laboratory and clinical interference with Tg measurements were assessed. The course of TgAb concentration and disease status were compared during 3 years after initial treatment. The agglutination test failed to detect all titers < 10 IU/mL (ICMA). Interference from TgAb was common at high titers, but even low antibody titers (< 5 IU/mL) were able to interfere with Tg measurement. Cases of distant metastases with undetectable Tg (by IRMA) and those apparently free of disease and without thyroid remnants with Tg> 2 ng/ml (by RIA) were identified among patients with TgAb. The exogenous Tg recovery test was normal (> 80%) by the two methods in 22% of patients with TgAb and confirmed laboratory interference. Absence of reduction in TgAb levels was a marker of persistent disease. In conclusion, TgAb should be determined by immunoassays; interference with Tg measurements occurred mainly but not always at high concentrations, with a normal Tg recovery test not excluding this interference. The behavior of TgAb is related to disease persistence or cure.
authors.affiliation: Division of Thyroid, Department of Endocrinology and Metabolism, Santa Casa de Belo Horizonte, Belo Horizonte, MG. cepcem.bhz@terra.com.br
authors.forename: Pedro Weslley S
authors.initials: PW
authors.lastname: Rosário
authors.forename: Frederico F Ribeiro
authors.initials: FF
authors.lastname: Maia
authors.forename: Tales Alvarenga
authors.initials: TA
authors.lastname: Fagundes
authors.forename: Flávio Palhano
authors.initials: FP
authors.lastname: Vasconcelos
authors.forename: Ludmilla David
authors.initials: LD
authors.lastname: Cardoso
authors.forename: Saulo
authors.initials: S
authors.lastname: Purisch
mesh_terms: D000328:Adult; D000372:Agglutination Tests; D001323:Autoantibodies / Q000097:blood*; D002277:Carcinoma / Q000097:blood* / Q000276:immunology; D005260:Female; D006801:Humans; D007118:Immunoassay; D008297:Male; D013954:Thyroglobulin / Q000097:blood* / Q000276:immunology*; D013964:Thyroid Neoplasms / Q000097:blood* / Q000276:immunology
chemical_list: D001323:Autoantibodies; D013954:Thyroglobulin