title: Thyroglobulin Liquid Chromatography-Tandem Mass Spectrometry Has a Low Sensitivity for Detecting Structural Disease in Patients with Antithyroglobulin Antibodies.
abstract: Thyroglobulin (Tg) measurement in patients with positive antithyroglobulin antibodies (anti-TgAbs) is not reliable. Tg measurement using liquid chromatography-tandem mass spectrometry (LC/MS) may be useful in this setting.
  
  
  
  This is a retrospective study with the objective of determining the accuracy of Tg-LC/MS in patients with thyroid cancer with anti-TgAbs. All patients with follicular cell-derived thyroid cancer (TC) who had thyroglobulin measured using LC/MS assay from November 1, 2013, to November 7, 2014, were evaluated. The frequency of detectable Tg-LC/MS was evaluated, with a functional sensitivity (FS) of 0.5 ng/mL in patients with structural disease. Then performance of Tg-LC/MS versus Tg immunometric assay (IMA) was compared using either Immulite assay (Tg-1) with a FS of 0.9 ng/mL or Beckman assay (Tg-B) with a FS of 0.1 ng/mL in detecting structural disease in patients with positive anti-TgAbs.
  
  
  
  A total of 154 consecutive patients were included in this evaluation. Of these, 116 (75%) patients were positive for anti-TgAbs. In patients with structural disease and positive anti-TgAbs, Tg-LC/MS was undetectable in 43.7% of patients. Then the diagnostic accuracy for structural disease of Tg-LC/MS was compared with each Tg-IMA assay separately. In the 26 patients with positive anti-TgAbs where a Tg-I assay was used, the sensitivity and specificity for detecting structural disease were 33.3% and 88.2%, respectively, for the Tg-I assay, and 44.4% and 94.1%, respectively, for the Tg-LC/MS assay. In the 74 patients with positive anti-TgAbs where Tg-B was used, the sensitivity and specificity for detection of structural disease were 72.7% and 71.4%, respectively, for the Tg-B assay, and 62.6% and 93.7%, respectively, for the Tg-LC/MS assay.
  
  
  
  In patients with thyroid cancer with positive anti-TgAbs, Tg-LC/MS was frequently undetectable and was less sensitive for detecting disease than a Tg assay was with a functional sensitivity of 0.1 ng/mL. For patients with detectable Tg-LC/MS and anti-TgAbs, use of the assay for monitoring requires further prospective studies.
authors.affiliation: 1 Division of Endocrinology, Diabetes, and Metabolism, The Ohio State University and Arthur G. James Cancer Center , Columbus, Ohio.
authors.forename: Umal
authors.initials: U
authors.lastname: Azmat
authors.affiliation: 2 Center for Biostatistics, The Ohio State University and Arthur G. James Cancer Center , Columbus, Ohio.
authors.forename: Kyle
authors.initials: K
authors.lastname: Porter
authors.affiliation: 3 Division of Human Genetics, The Ohio State University and Arthur G. James Cancer Center , Columbus, Ohio.
authors.forename: Leigha
authors.initials: L
authors.lastname: Senter
authors.affiliation: 1 Division of Endocrinology, Diabetes, and Metabolism, The Ohio State University and Arthur G. James Cancer Center , Columbus, Ohio.
authors.forename: Matthew D
authors.initials: MD
authors.lastname: Ringel
authors.affiliation: 1 Division of Endocrinology, Diabetes, and Metabolism, The Ohio State University and Arthur G. James Cancer Center , Columbus, Ohio.
authors.forename: Fadi
authors.initials: F
authors.lastname: Nabhan
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001323:Autoantibodies / Q000032:analysis*; D002648:Child; D002853:Chromatography, Liquid; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D053719:Tandem Mass Spectrometry; D013954:Thyroglobulin / Q000276:immunology*; D013964:Thyroid Neoplasms / Q000276:immunology*; D055815:Young Adult
chemical_list: D001323:Autoantibodies; D013954:Thyroglobulin
keywords: antithyroglobulin antibodies; thyroglobulin mass spectrometry; thyroid cancer