title: Monitoring differentiated thyroid cancer patients with negative serum thyroglobulin. Diagnostic implication of TSH-stimulated antithyroglobulin antibody.
abstract: OBJECTIVE
  Serum antithyroglobulin antibody (TgAb) has been reported as a surrogate marker for differentiated thyroid cancer (DTC) in some conditions. We investigated changes in serum TgAb levels after stimulation with thyroid-stimulating hormone (TSH) and the clinical implications for monitoring DTC.
  
  
  METHODS
  We retrospectively enrolled 53 DTC patients who had undergone total thyroidectomy and were negative for serum Tg and positive for TgAb. Patients underwent high-dose radioactive iodine treatment, and serum TgAb was measured before (TgAbBAS) and after TSH stimulation (TgAbSTIM). TgAb was followed up 6 to 12 months later (TgAbF/U). The change in TgAb after TSH stimulation (∆TgAbSTIM) was calculated as a percentage of the baseline level. Patient disease status was classified into no residual disease (ND) and residual or recurred disease (RD) by follow-up imaging studies and pathologic data. The characteristics and diagnostic value of serum TgAb levels and ∆ TgAbSTIM were investigated with respect to disease status.
  
  
  RESULTS
  38 patients were in the ND group and 15 were in the RD group. TgAbBAS, TgAbSTIM and TgAbF/U were significantly higher in the RD compared to the ND group (p = 0.0008, 0.0002, and < 0.0001, respectively). ∆TgAbSTIM was also significantly higher in the RD group (p = 0.0009). In the patients who presented with obviously high (≥ 50%) or low (< -50%) ∆ TgAbSTIM, the proportions in the RD group were markedly different at 100% and 7%, respectively. ∆ TgAbSTIM had significant diagnostic value for RD (p < 0.001).
  
  
  CONCLUSIONS
  The change in serum TgAb level after TSH stimulation is different between the RD and ND groups, and thus, it may be used as a surrogate diagnostic marker for DTC when the serum Tg is negative and TgAb is positive.
authors.forename: H-Y
authors.initials: HY
authors.lastname: Nam
authors.affiliation: Jin Chul Paeng, M.D., Ph.D., Seoul National University Hospital, 101, Daehak-ro, Jongno-gu, Seoul, Korea, Tel. 82-2-2072-3793, Fax 82-2-745-7690, E-mail: paengjc@snu.ac.kr.
authors.forename: J C
authors.initials: JC
authors.lastname: Paeng
authors.forename: J-K
authors.initials: JK
authors.lastname: Chung
authors.forename: K W
authors.initials: KW
authors.lastname: Kang
authors.forename: G J
authors.initials: GJ
authors.lastname: Cheon
authors.forename: Y
authors.initials: Y
authors.lastname: Kim
authors.forename: D J
authors.initials: DJ
authors.lastname: Park
authors.forename: Y J
authors.initials: YJ
authors.lastname: Park
authors.forename: H S
authors.initials: HS
authors.lastname: Min
authors.forename: D S
authors.initials: DS
authors.lastname: Lee
mesh_terms: D001323:Autoantibodies / Q000097:blood*; D014408:Biomarkers, Tumor / Q000097:blood*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000097:blood* / Q000175:diagnosis*; D018365:Neoplasm, Residual; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013954:Thyroglobulin / Q000097:blood*; D013964:Thyroid Neoplasms / Q000097:blood* / Q000175:diagnosis* / Q000601:surgery; D013972:Thyrotropin; D016896:Treatment Outcome
chemical_list: D001323:Autoantibodies; D014408:Biomarkers, Tumor; C006606:anti-thyroglobulin; D013972:Thyrotropin; D013954:Thyroglobulin
keywords: Differentiated thyroid cancer; antithyroglobulin antibody; thyroglobulin; thyroid-stimulating hormone