title: Unstimulated highly sensitive thyroglobulin in follow-up of differentiated thyroid cancer patients: a meta-analysis.
abstract: BACKGROUND
  Serum thyroglobulin (Tg) is an indicator of differentiated thyroid cancer (DTC) relapse.
  
  
  OBJECTIVE
  Our objective was to conduct a meta-analysis of published data about the diagnostic performance of highly sensitive serum Tg (hsTg) during levothyroxine therapy in DTC follow-up.
  
  
  METHODS
  We performed a comprehensive literature search of PubMed/MEDLINE and Scopus for studies published until July 2013.
  
  
  METHODS
  Studies investigating the diagnostic performance of basal hsTg in monitoring DTC were eligible. Exclusion criteria were 1) articles not within the field of interest; 2) reviews, letters, or conference proceedings; 3) articles evaluating serum Tg measurement with a functional sensitivity >0.1 ng/mL; 4) overlap in patient data; and 5) insufficient data to reassess diagnostic performance of basal serum hsTg.
  
  
  METHODS
  Information was collected concerning basic study data, patient characteristics, and technical aspects. For each study, the number of true-positive, false-positive, true-negative, and false-negative findings for basal hsTg, considering stimulated Tg measurement as a reference standard, were recorded.
  
  
  RESULTS
  Pooled data demonstrated that the negative predictive value of hsTg was 97% and 99% considering a stimulated Tg measurement >1 ng/mL and >2 ng/mL as cutoffs for positivity, respectively. Despite the high pooled sensitivity of basal hsTg, the pooled specificity, accuracy, and positive predictive value were insufficient to completely substitute for a stimulated Tg measurement.
  
  
  CONCLUSIONS
  Basal hsTg measurement has a very high negative predictive value but an insufficient positive predictive value for monitoring DTC patients. Therefore, a Tg stimulation test can be avoided in patients with an undetectable basal hsTg, whereas a stimulated Tg measurement should be considered when hsTg levels are detectable.
authors.affiliation: Department of Nuclear Medicine and PET/CT Center (L.G., G.T., L.C.), Oncology Institute of Southern Switzerland, CH-6500 Bellinzona, Switzerland; Nuclear Medicine Research Center (R.S.), Mashhad University of Medical Sciences, 91766-99199 Mashhad, Iran; Section of Endocrinology and Diabetology (P.T.), Ospedale Israelitico, 00148 Rome, Italy; and Department of Nuclear Medicine (F.A.V.), Rheinisch-Westfällische Technische Hochschule University Hospital Aachen, 52074 Aachen, Germany.
authors.forename: Luca
authors.initials: L
authors.lastname: Giovanella
authors.forename: Giorgio
authors.initials: G
authors.lastname: Treglia
authors.forename: Ramin
authors.initials: R
authors.lastname: Sadeghi
authors.forename: Pierpaolo
authors.initials: P
authors.lastname: Trimboli
authors.forename: Luca
authors.initials: L
authors.lastname: Ceriani
authors.forename: Frederik A
authors.initials: FA
authors.lastname: Verburg
mesh_terms: D014408:Biomarkers, Tumor / Q000097:blood*; D006801:Humans; D009364:Neoplasm Recurrence, Local / Q000097:blood / Q000175:diagnosis*; D013954:Thyroglobulin / Q000097:blood*; D013960:Thyroid Function Tests; D013964:Thyroid Neoplasms / Q000097:blood / Q000175:diagnosis* / Q000188:drug therapy
chemical_list: D014408:Biomarkers, Tumor; D013954:Thyroglobulin