title: Thyroglobulin before ablation and correlation with posttreatment scanning.
abstract: OBJECTIVE
  To determine the usefulness of thyroglobulin (Tg) before ablation and the correlation with posttreatment scanning in patients with thyroid carcinoma.
  
  
  METHODS
  Prospective.
  
  
  METHODS
  Tg during hypothyroidism was determined in 212 patients after thyroidectomy and before ablation. The disease stage was based on clinical examination, Tg, posttherapy scanning, other imaging methods, and histologic confirmation in selected cases.
  
  
  RESULTS
  One hundred sixty-four patients presented thyroid remnants only, 31 had lymph node metastases, and 17 had distant metastases. Posttreatment scanning showed a sensitivity of 71% for lymph node and of 94.1% for distant metastases. Ectopic uptake was observed in 5.6% of patients with Tg less than 1 ng/mL, in 9% with levels from 1 to 5 ng/mL, in 10.7% with Tg from 5 to 10 ng/mL, and in 51% with Tg greater than 10 ng/mL. The sensitivity of Tg for metastases was 73 and 66.5% and specificity was 73 and 88.4% at a cut-off value of 5 and 10 ng/mL, respectively.
  
  
  CONCLUSIONS
  Postoperative Tg less than 10 ng/mL rarely show distant metastases and because these metastases were observed in 31% of patients with values greater than 10 ng/mL, this criterion can be selected for the indication of imaging methods, in addition to neck ultrasound (US). For cases with Tg less than 10 ng/mL, US is necessary because even patients with undetectable Tg had lymph node metastases. The same cut-off can be used for the indication of radioiodine therapy even in the absence of any evidence of disease because 51% of the patients with Tg greater than 10 ng/mL showed ectopic uptake on posttreatment scanning.
authors.affiliation: Department of Thyroid, Santa Casa de Belo Horizonte, Minas Gerais, Brazil. pedrorosario@globo.com
authors.forename: Pedro Weslley Souza
authors.initials: PW
authors.lastname: de Rosário
authors.forename: Valéria C
authors.initials: VC
authors.lastname: Guimarães
authors.forename: Frederico Fernandes Ribeiro
authors.initials: FF
authors.lastname: Maia
authors.forename: Tales Alvarenga
authors.initials: TA
authors.lastname: Fagundes
authors.forename: Saulo
authors.initials: S
authors.lastname: Purisch
authors.forename: Eduardo Lanza
authors.initials: EL
authors.lastname: Padrao
authors.forename: Leonardo Lamego
authors.initials: LL
authors.lastname: Rezende
authors.forename: Alvaro Luis
authors.initials: AL
authors.lastname: Barroso
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002291:Carcinoma, Papillary / Q000097:blood* / Q000601:surgery*; D002648:Child; D005260:Female; D006801:Humans; D007037:Hypothyroidism / Q000097:blood; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D012680:Sensitivity and Specificity; D013954:Thyroglobulin / Q000097:blood*; D013964:Thyroid Neoplasms / Q000097:blood* / Q000601:surgery*; D013965:Thyroidectomy
chemical_list: D013954:Thyroglobulin