title: Human chorionic gonadotropin discriminatory zone in ectopic pregnancy: does assay harmonization matter?
abstract: OBJECTIVE
  To determine the effect that lack of hCG assay harmonization has on the interpretation of a serum hCG concentration with regards to the hCG discriminatory zone.
  
  
  METHODS
  A multisite method comparison study.
  
  
  METHODS
  Clinical laboratories.
  
  
  METHODS
  Eighty serum samples containing various concentrations of hCG.
  
  
  METHODS
  None.
  
  
  METHODS
  Concentrations of hCG obtained from seven hCG reagent platforms.
  
  
  RESULTS
  The hCG concentrations were significantly different across hCG reagent platforms. Seventy-one percent of assay pairs showed significant differences with samples selected based on hCG concentrations between 1,500 and 3,500 IU/L as determined by a comparative method. Relative to the comparative method, the calculated hCG discriminatory zones for five assays were within 9%, and one assay was within 40% of the target concentrations of 1,500 and 3,500 IU/L.
  
  
  CONCLUSIONS
  Despite significant differences in hCG concentrations across hCG immunoassays, an hCG concentration within a discriminatory zone of 1,500-3,500 IU/L can be used for all but one commonly used hCG reagent platform.
authors.affiliation: Department of Pathology, University of Utah School of Medicine, Salt Lake City, Utah.
authors.forename: Diana
authors.initials: D
authors.lastname: Desai
authors.affiliation: ARUP Institute for Clinical and Experimental Pathology, ARUP Laboratories, Salt Lake City, Utah.
authors.forename: Jun
authors.initials: J
authors.lastname: Lu
authors.affiliation: ARUP Institute for Clinical and Experimental Pathology, ARUP Laboratories, Salt Lake City, Utah.
authors.forename: Sara P
authors.initials: SP
authors.lastname: Wyness
authors.affiliation: Northern California Kaiser Permanente Regional Laboratory, Berkeley, California.
authors.forename: Dina N
authors.initials: DN
authors.lastname: Greene
authors.affiliation: HealthPartners/Regions Hospital, St. Paul, Minnesota.
authors.forename: Kalen N
authors.initials: KN
authors.lastname: Olson
authors.affiliation: PAML, Spokane, Washington.
authors.forename: Carmen L
authors.initials: CL
authors.lastname: Wiley
authors.affiliation: Department of Pathology, University of Utah School of Medicine, Salt Lake City, Utah; ARUP Institute for Clinical and Experimental Pathology, ARUP Laboratories, Salt Lake City, Utah. Electronic address: david.grenache@path.utah.edu.
authors.forename: David G
authors.initials: DG
authors.lastname: Grenache
mesh_terms: D015415:Biomarkers / Q000097:blood; D006063:Chorionic Gonadotropin / Q000097:blood*; D019411:Clinical Laboratory Techniques / Q000592:standards*; D005260:Female; D005865:Gestational Age; D006801:Humans; D059021:Laboratory Proficiency Testing; D015588:Observer Variation; D011237:Predictive Value of Tests; D011247:Pregnancy; D011271:Pregnancy, Ectopic / Q000097:blood / Q000175:diagnosis* / Q000000981:diagnostic imaging; D015203:Reproducibility of Results; D016216:Ultrasonography, Prenatal; D014481:United States
chemical_list: D015415:Biomarkers; D006063:Chorionic Gonadotropin
keywords: Ectopic pregnancy; hCG; hCG discriminatory zone; harmonization