title: Performance characteristics of the UniCel DxI 800 immunoassay for the maternal serum quadruple test, including median values for each week of gestation, in Korean women.
abstract: BACKGROUND
  Maternal serum prenatal quadruple screening includes testing for alpha-fetoprotein (AFP), human chorionic gonadotrophin (hCG), unconjugated estriol (uE3), and dimeric inhibin A (DIA). We evaluated quadruple screening using an automated platform and looked for any ethnic differences in the median values of each marker.
  
  
  METHODS
  We measured the concentrations of each quadruple test analyte using the UniCel DxI 800 system (Beckman Coulter, USA) in 788 Korean mid-trimester maternal serum samples and calculated their median values using Benetech software (Benetech, Canada). We also compared the results with those obtained using the Immulite 2000 assay (Siemens Healthcare Diagnostics, USA) or ELISA (DSL, USA) in 442 samples.
  
  
  RESULTS
  We obtained mid-trimester median values for each marker. The following are the comparative results for each test using the Immulite 2000 assay or ELISA (x) and the UniCel DxI 800 immunoassay (y): AFP, y=1.10x+0.01, r=0.925; uE3, y=0.28x+0.24, r=0.885; hCG, y=1.22x-3047.8, r=0.944; and DIA, y=0.86x+15.31, r=0.833. Assay results for each of the four markers showed good correlations. However, significant biases necessitated new median calculations of prenatal risk estimates in all four tests.
  
  
  CONCLUSIONS
  We established gestational age-specific second-trimester median values for four markers in Korean samples using the UniCel DxI 800 immunoassay system. Despite significant bias, there were good correlations between the results obtained using the UniCel DxI 800 immunoassay and those obtained using the Immulite 2000 assay.
authors.affiliation: Department of Laboratory Medicine, Yonsei University College of Medicine, Seoul, Korea. jeongho@yuhs.ac
authors.forename: Jeong Hoon
authors.initials: JH
authors.lastname: Lee
authors.forename: Yongjung
authors.initials: Y
authors.lastname: Park
authors.forename: Borum
authors.initials: B
authors.lastname: Suh
authors.forename: Seon Mi
authors.initials: SM
authors.lastname: Song
authors.forename: Oh Hun
authors.initials: OH
authors.lastname: Kwon
authors.forename: Jeong Ho
authors.initials: JH
authors.lastname: Kim
mesh_terms: D015415:Biomarkers / Q000097:blood; D006063:Chorionic Gonadotropin / Q000097:blood; D004797:Enzyme-Linked Immunosorbent Assay; D004964:Estriol / Q000097:blood; D005260:Female; D005865:Gestational Age; D006801:Humans; D007118:Immunoassay / Q000295:instrumentation / Q000379:methods*; D007265:Inhibins / Q000097:blood; D011247:Pregnancy; D011262:Pregnancy Trimester, Second; D011296:Prenatal Diagnosis; D012016:Reference Values; D056910:Republic of Korea; D000509:alpha-Fetoproteins / Q000032:analysis
chemical_list: D015415:Biomarkers; D006063:Chorionic Gonadotropin; D000509:alpha-Fetoproteins; D007265:Inhibins; D004964:Estriol