title: Performance characteristics of the Beckman Coulter total βhCG (5th IS) assay.
abstract: BACKGROUND
  Beckman Coulter recently released the first commercially available hCG reagent calibrated against the 5th International Standard (IS) for hCG (total βhCG (5th IS)). We performed a comprehensive analytical validation of this reagent.
  
  
  METHODS
  Precision experiments were completed using 3 concentrations of commercial quality control material. Linearity, sample stability, and analytical sensitivity were evaluated using pools of human serum. Reportable range was assessed by comparing manual dilutions to those performed by the instrument. Male and female reference intervals were established using residual serum specimens submitted for routine testing. Inter-lot variability of hCG assay reagent was assessed by analyzing serum specimens with detectable hCG using 2 different reagent lots. Inter-assay variability was established using 203 serum specimens analyzed for hCG on 6 different reagent platforms.
  
  
  RESULTS
  Inter-day precision showed a CV of <6.0% for all concentrations of QC material. LOB, LOD, and LOQ were determined to be 0.3, 0.4, and 0.6 U/l, respectively. The Access (5th IS) reagent has an average positive bias of approximately 20% when compared to most platforms and the previous generation Beckman hCG assay. Results were consistent between lots. Female reference intervals varied by age: <1.0 U/l (<41 y), <6.0 U/l (41-50 y), and <8.0 U/l (>50 y). Male reference intervals were <2.0 U/l.
  
  
  CONCLUSIONS
  The analytical performance of the total βhCG (5th IS) was established. Care should be taken to re-baseline patients needing serial monitoring and/or notify physicians when transitioning to the total βhCG (5th IS) reagent.
authors.affiliation: Kaiser Permanente, TPMG Northern California Regional Laboratory, Berkeley, CA, United States. Electronic address: dina.n.greene@kp.org.
authors.forename: Dina N
authors.initials: DN
authors.lastname: Greene
authors.affiliation: Kaiser Permanente, TPMG Northern California Regional Laboratory, Berkeley, CA, United States.
authors.forename: Matthew S
authors.initials: MS
authors.lastname: Petrie
authors.affiliation: Nationwide Children's Hospital, Department of Laboratory Medicine and Pathology, Columbus, OH, United States.
authors.forename: Amy L
authors.initials: AL
authors.lastname: Pyle
authors.affiliation: Kaiser Permanente, TPMG Northern California Regional Laboratory, Berkeley, CA, United States.
authors.forename: Sandy M
authors.initials: SM
authors.lastname: Kamer
authors.affiliation: University of Utah School of Medicine, Department of Pathology, Salt Lake City, UT, United States; ARUP Laboratories, Salt Lake City, UT, United States.
authors.forename: David G
authors.initials: DG
authors.lastname: Grenache
mesh_terms: D000328:Adult; D018997:Chorionic Gonadotropin, beta Subunit, Human / Q000097:blood* / Q000592:standards; D005260:Female; D006801:Humans; D007118:Immunoassay / Q000592:standards; D008297:Male; D008875:Middle Aged; D012016:Reference Values
chemical_list: D018997:Chorionic Gonadotropin, beta Subunit, Human
keywords: 5th IS; Beckman Access; Calibration; Immunoassay variability; Validation; hCG