title: Serum thyroglobulin is a poor diagnostic biomarker of malignancy in follicular and Hurthle-cell neoplasms of the thyroid.
abstract: BACKGROUND
  Serum thyroglobulin (Tg) is the most accurate biomarker for thyroid cancer recurrence. However, some clinicians measure preoperative Tg as a diagnostic cancer marker despite lack of supporting evidence. We examined whether Tg accurately predicts malignancy in follicular or Hürthle-cell neoplasms.
  
  
  METHODS
  We reviewed 366 patients who underwent thyroidectomies for follicular/Hürthle-cell neoplasms. We compared Tg in malignant versus benign tumors by univariate and receiver-operator characteristic analyses. We also examined several Tg-derived indices that normalized Tg to known confounding factors including nodule size, thyroid function, and type of Tg assay.
  
  
  RESULTS
  Thirty-nine patients met inclusion criteria for analysis. There were no differences between malignant (n = 16) and benign (n = 23) lesions in Tg or any of the normalized indexes. Receiver-operator characteristic analysis revealed an area under the curve of .59. Lesions with Tg levels greater than 500 mug/L had a positive predictive value of .75.
  
  
  CONCLUSIONS
  Tg has poor accuracy for predicting malignancy in follicular or Hürthle-cell thyroid neoplasms.
authors.affiliation: Department of Surgery, University of California-San Francisco, 513 Parnassus Ave., San Francisco, CA 94143-0470, USA. insoo.suh@ucsfmedctr.org
authors.forename: Insoo
authors.initials: I
authors.lastname: Suh
authors.forename: Menno R
authors.initials: MR
authors.lastname: Vriens
authors.forename: Marlon A
authors.initials: MA
authors.lastname: Guerrero
authors.forename: Ann
authors.initials: A
authors.lastname: Griffin
authors.forename: Wen T
authors.initials: WT
authors.lastname: Shen
authors.forename: Quan-Yang
authors.initials: QY
authors.lastname: Duh
authors.forename: Orlo H
authors.initials: OH
authors.lastname: Clark
authors.forename: Electron
authors.initials: E
authors.lastname: Kebebew
mesh_terms: D018263:Adenocarcinoma, Follicular / Q000097:blood / Q000473:pathology* / Q000601:surgery; D018249:Adenoma, Oxyphilic / Q000097:blood / Q000473:pathology* / Q000601:surgery; D000328:Adult; D015415:Biomarkers / Q000097:blood; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012372:ROC Curve; D015203:Reproducibility of Results; D012189:Retrospective Studies; D013954:Thyroglobulin / Q000097:blood*; D013964:Thyroid Neoplasms / Q000097:blood* / Q000473:pathology* / Q000601:surgery; D013965:Thyroidectomy
chemical_list: D015415:Biomarkers; D013954:Thyroglobulin