title: Two-center clinical evaluation of a new automated fluorometric immunoassay for the quantitative analysis of total betaeta-human chorionic gonadotropin.
abstract: OBJECTIVE
  This study evaluated the quantitative total betahCG assay on the Stratus CS point-of-care instrument at two medical centers.
  
  
  METHODS
  Analytical sensitivity, linearity, within-run and total imprecision, interferences, dilution recovery, method comparison (Dimension RxL), comparison of matched heparinized whole blood and plasma samples, and determination of the normal reference interval were studied.
  
  
  RESULTS
  Analytical sensitivity was <0.5 IU/L. The assay's linear range was 0 to 1250 IU/L; the clinical reportable range was up to 50,000 IU/L. Within-run imprecision (CV) at both low (<20 IU/L) and elevated (760 IU/L) betahCG concentrations were <4%. Total imprecision for three QC levels and two pools were <4%. Method comparison showed Stratus CS betahCG = 0.98 +/- 0.01* Dimension RxL hCG -0.11 +/- 2.69 (n = 136; r = 0.996; Sy/x = 27.7). Matched heparinized whole blood/plasma sample-comparison showed: whole blood = 1.05*Plasma + 0.37 +/- 1.29 (n = 41; r = 1.000; Sy/x = 7.57). Mean dilution recovery was 99% (range: 95% to 103%). None of the 52 drugs tested, lipemia, icterus, hemolysis, LH, FSH, TSH, hGH or prolactin represented a significant interference with the assay. Reference intervals were <0.5 IU/L for males (n = 123) and <3.0 IU/L for nonpregnant females (n = 120).
  
  
  CONCLUSIONS
  The Stratus CS betahCG test offers the advantage of quantitative measurement of total betahCG in whole blood at the point of care and is suitable for clinical use.
authors.affiliation: Department of Pathology, University of Maryland School of Medicine, Baltimore, Maryland 21201, USA.
authors.forename: Hassan M E
authors.initials: HM
authors.lastname: Azzazy
authors.forename: Liana Frances
authors.initials: LF
authors.lastname: Romero
authors.forename: Lee
authors.initials: L
authors.lastname: Hall
authors.forename: Doris
authors.initials: D
authors.lastname: Ruttle
authors.forename: Robert H
authors.initials: RH
authors.lastname: Christenson
mesh_terms: D002138:Calibration; D018997:Chorionic Gonadotropin, beta Subunit, Human / Q000032:analysis* / Q000097:blood; D005260:Female; D015200:Fluoroimmunoassay / Q000379:methods*; D006801:Humans; D008297:Male; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D018997:Chorionic Gonadotropin, beta Subunit, Human