title: The third/second generation PTH assay ratio as a marker for parathyroid carcinoma: evaluation using an automated platform.
abstract: BACKGROUND
  Parathyroid carcinoma (PCa) is rare and often difficult to differentiate initially from benign disease. Because PCa oversecretes amino PTH that is detected by third-generation but not by second-generation PTH assays, the normal 3rd/2nd generation PTH ratio (<1) is inverted in PCa (ie, >1).
  
  
  OBJECTIVE
  The objective of the investigation was to study the utility and advantages of automated 3rd/2nd generation PTH ratio measurements using the Liaison XL platform over existing manual techniques.
  
  
  METHODS
  The study was conducted at a tertiary-referral academic center.
  
  
  METHODS
  This was a retrospective laboratory study.
  
  
  METHODS
  Eleven patients with advanced PCa (mean age 56.0 y). The controls were patients with primary-hyperparathyroidism (n = 144; mean age 53.8 y), renal transplantation (n = 41; mean age 50.6 y), hemodialysis (n = 80; mean age 65.2 y), and healthy elderly subjects (n = 40; mean age 72.6 y).
  
  
  RESULTS
  The median (interquartile range) 3rd/2nd generation PTH ratio was 1.16 (1.10-1.38) in the PCa group, which was significantly higher than the control groups: hemodialysis: 0.74 (0.71-0.75); renal transplant: 0.77 (0.73-0.79); primary hyperparathyroidism: 0.76 (0.74-0.78); healthy elderly: 0.80 (0.74-0.83). An inverted 3rd/2nd-generation PTH ratio (>1) was seen in 9 of 11 PCa patients (81.8%) and in 7 of 305 controls (2.3%): 3 of 80 hemodialysis (3.8%), and 4 of 144 primary-hyperparathyroidism patients (2.8%). Of four PCa patients who had a normal PTH ratio with the manual method, two had an inverted 3rd/2nd-generation PTH ratio with the automated method.
  
  
  CONCLUSIONS
  Study of the 3rd/2nd-generation PTH ratio in large patient populations should be feasible using a mainstream automated platform like the Liaison XL. The current study confirms the utility of the inverted 3rd/2nd-generation PTH ratio as a marker of PCa (sensitivity: 81.8%; specificity: 97.3%).
authors.affiliation: Departments of Clinical Chemistry (E.C., M.-L.S., R.G.), Endocrinology (D.B., L.V., A.F.D., A.B.), and Nephrology (P.D.), Centre Hospitalier Universitaire de Liège, University of Liège, B-4000 Liège, Belgium.
authors.forename: Etienne
authors.initials: E
authors.lastname: Cavalier
authors.forename: Daniela
authors.initials: D
authors.lastname: Betea
authors.forename: Marie-Louise
authors.initials: ML
authors.lastname: Schleck
authors.forename: Romy
authors.initials: R
authors.lastname: Gadisseur
authors.forename: Laurent
authors.initials: L
authors.lastname: Vroonen
authors.forename: Pierre
authors.initials: P
authors.lastname: Delanaye
authors.forename: Adrian F
authors.initials: AF
authors.lastname: Daly
authors.forename: Albert
authors.initials: A
authors.lastname: Beckers
mesh_terms: D000328:Adult; D000368:Aged; D057205:Automation, Laboratory; D014408:Biomarkers, Tumor / Q000032:analysis* / Q000097:blood; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D007118:Immunoassay / Q000295:instrumentation / Q000379:methods; D008163:Luminescent Measurements / Q000295:instrumentation / Q000379:methods; D008297:Male; D008875:Middle Aged; D010281:Parathyroid Hormone / Q000032:analysis* / Q000097:blood; D010282:Parathyroid Neoplasms / Q000097:blood / Q000175:diagnosis*; D012189:Retrospective Studies
chemical_list: D014408:Biomarkers, Tumor; D010281:Parathyroid Hormone