title: Change of serum antithyroglobulin antibody levels is useful for prediction of clinical recurrence in thyroglobulin-negative patients with differentiated thyroid carcinoma.
abstract: OBJECTIVE
  The aim of the study was to evaluate the usefulness of the antithyroglobulin autoantibody (TgAb) value at 6-12 months after remnant ablation in predicting recurrence in differentiated thyroid carcinoma patients who had undetectable thyroglobulin (Tg) values. The change in TgAb concentration measured between the time of remnant ablation (TgAb1) and 6-12 months thereafter (TgAb2) was also evaluated as a possible prognostic indicator.
  
  
  METHODS
  Patients with differentiated thyroid carcinoma who underwent total thyroidectomy followed by (131)I remnant ablation between 1995 and 2003 at the Asan Medical Center (Seoul, Korea) were enrolled. Of these, 824 patients with undetectable Tg at 6-12 months after remnant ablation during thyroid hormone withdrawal were the subjects of this study.
  
  
  RESULTS
  TgAb2 was positive in 56 patients. Ten of 56 patients (18%) with positive TgAb2 had recurrence, whereas only 10 of 768 patients (1%) with negative TgAb2 had recurrence during 73.6 months of follow-up (P < 0.001). The change between TgAb1 and TgAb2 levels was evaluated in patients with positive TgAb2. TgAb concentration decreased by more than 50% in 21 patients (group 1) and by less than 50% in 16 patients (group 2), and it increased in 19 patients (group 3). The recurrence rates in groups 1, 2, and 3 were 0, 19, and 37%, respectively (P = 0.016).
  
  
  CONCLUSIONS
  Serum TgAb levels measured at 6-12 months after remnant ablation could predict recurrence in patients with undetectable Tg values. In patients with undetectable Tg and positive TgAb values, a change in TgAb concentration during the early postoperative period may be a prognostic indicator of recurrence.
authors.affiliation: Department of Endocrinology and Metabolism, Asan Medical Center, University of Ulsan College of Medicine, 388-1 Pungnap-dong, Songpa-gu, Seoul 138-736, Korea.
authors.forename: Won Gu
authors.initials: WG
authors.lastname: Kim
authors.forename: Jong Ho
authors.initials: JH
authors.lastname: Yoon
authors.forename: Won Bae
authors.initials: WB
authors.lastname: Kim
authors.forename: Tae Yong
authors.initials: TY
authors.lastname: Kim
authors.forename: Eui Young
authors.initials: EY
authors.lastname: Kim
authors.forename: Jung Min
authors.initials: JM
authors.lastname: Kim
authors.forename: Jin-Sook
authors.initials: JS
authors.lastname: Ryu
authors.forename: Gyungyub
authors.initials: G
authors.lastname: Gong
authors.forename: Suck Joon
authors.initials: SJ
authors.lastname: Hong
authors.forename: Young Kee
authors.initials: YK
authors.lastname: Shong
mesh_terms: D000328:Adult; D000368:Aged; D000906:Antibodies / Q000097:blood*; D015415:Biomarkers; D003131:Combined Modality Therapy; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007457:Iodine Radioisotopes / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012008:Recurrence; D013954:Thyroglobulin / Q000097:blood* / Q000276:immunology*; D013964:Thyroid Neoplasms / Q000175:diagnosis* / Q000276:immunology* / Q000628:therapy; D013965:Thyroidectomy; D013967:Thyroiditis, Autoimmune / Q000175:diagnosis / Q000628:therapy; D013972:Thyrotropin / Q000097:blood; D051598:Whole Body Imaging
chemical_list: D000906:Antibodies; D015415:Biomarkers; D007457:Iodine Radioisotopes; D013972:Thyrotropin; D013954:Thyroglobulin