Change of serum antithyroglobulin antibody levels is useful for prediction of clinical recurrence in thyroglobulin-negative patients with differentiated thyroid carcinoma.
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.
Kim
Won Gu
WG
Department of Endocrinology and Metabolism, Asan Medical Center, University of Ulsan College of Medicine, 388-1 Pungnap-dong, Songpa-gu, Seoul 138-736, Korea.
Yoon
Jong Ho
JH
Kim
Won Bae
WB
Kim
Tae Yong
TY
Kim
Eui Young
EY
Kim
Jung Min
JM
Ryu
Jin-Sook
JS
Gong
Gyungyub
G
Hong
Suck Joon
SJ
Shong
Young Kee
YK
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
D000906:Antibodies; D015415:Biomarkers; D007457:Iodine Radioisotopes; D013972:Thyrotropin; D013954:Thyroglobulin