title: Analytical and clinical evaluation of a novel high-sensitivity assay for measurement of soluble ST2 in human plasma--the Presage ST2 assay.
abstract: BACKGROUND
  The protein ST2 is a member of the interleukin-1 receptor family. Blood concentrations of the soluble isoform of ST2 (sST2) are increased in inflammatory diseases and in heart disease and are considered a prognostic marker in both. The aim of this study was the analytical and clinical evaluation of the novel Presage ST2 assay for the determination of sST2 in human plasma.
  
  
  METHODS
  We evaluated precision and linearity of the assay, analyte stability, and biological variability, determined reference values, performed a method comparison with an established ELISA, and quantified sST2 concentrations in various diseases.
  
  
  RESULTS
  Within-run and total coefficients of variation were <2.5% and <4.0%. The method was linear across the whole measurement range of the assay. The analyte was stable for 48 h at room temperature, for 7 days at 4 degrees C, and for at least 2 months at -20 degrees C and -80 degrees C. The reference change value for healthy individuals was 30%. Age-independent reference values were 3-28 U/mL in males, and 2-16 U/mL in females. The method comparison revealed a high proportional bias. sST2 plasma concentrations were increased modestly in heart failure and moderately in pneumonia and chronic obstructive pulmonary disease. Patients with sepsis exhibited highly elevated sST2 values. In patients with chronic renal disease, however, there was no difference compared to healthy individuals.
  
  
  CONCLUSIONS
  The Presage ST2 assay meets the needs of quality specifications of laboratory medicine. The results of the clinical assay evaluation are novel with respect to sST2 in various diseases and should initiate further studies.
authors.affiliation: Department of Laboratory Medicine, Konventhospital Barmherzige Brueder Linz, Linz, Austria.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Dieplinger
authors.forename: James L
authors.initials: JL
authors.lastname: Januzzi
authors.forename: Martin
authors.initials: M
authors.lastname: Steinmair
authors.forename: Christian
authors.initials: C
authors.lastname: Gabriel
authors.forename: Werner
authors.initials: W
authors.lastname: Poelz
authors.forename: Meinhard
authors.initials: M
authors.lastname: Haltmayer
authors.forename: Thomas
authors.initials: T
authors.lastname: Mueller
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001774:Blood Chemical Analysis / Q000379:methods*; D005260:Female; D006801:Humans; D007118:Immunoassay; D000072179:Interleukin-1 Receptor-Like 1 Protein; D008297:Male; D008875:Middle Aged; D011956:Receptors, Cell Surface / Q000097:blood* / Q000737:chemistry*; D012995:Solubility
chemical_list: C079241:IL1RL1 protein, human; D000072179:Interleukin-1 Receptor-Like 1 Protein; D011956:Receptors, Cell Surface