title: Analytical characterization and clinical evaluation of an enzyme-linked immunosorbent assay for measurement of afamin in human plasma.
abstract: BACKGROUND
  Comparative proteomics has recently identified afamin, the newest member of the albumin gene family, as a potential biomarker for ovarian cancer. The aim of this study was the analytical and clinical evaluation of a sandwich enzyme-linked immunosorbent assay for the determination of afamin in human plasma.
  
  
  METHODS
  We evaluated precision, linearity, and detection limit of the assay, analyte stability and biological variability, determined reference values and quantified afamin concentrations in various diseases.
  
  
  RESULTS
  Within-run and total coefficients of variation were <10%. The method was linear across the tested measurement range. Detection limit was 7 mg/L for the assay. The analyte was stable for 24 h at room temperature, for 48 h at 4°C, and for at least one year at -20°C and -80°C. The reference change value for healthy individuals was 24%. Age- and sex-independent reference values in healthy blood donors were 45-99 mg/L (median 68 mg/L). In the clinical assay evaluation afamin plasma concentrations were modestly decreased in patients with heart failure. Patients with pneumonia or sepsis exhibited markedly decreased afamin plasma concentrations. However, patients with chronic renal disease or chronic obstructive pulmonary disease showed no difference in afamin plasma concentrations as compared to healthy individuals. Correlation analyses revealed an inverse association between afamin and inflammatory biomarkers.
  
  
  CONCLUSIONS
  The afamin assay meets quality specifications for laboratory medicine. The results of the clinical assay evaluation revealed novel insights with respect to afamin as a potential negative acute phase protein and should encourage further studies.
authors: Department of Laboratory Medicine, Konventhospital Barmherzige Brueder Linz, Linz, Austria. Electronic address: benjamin.dieplinger@bs-lab.at.
authors: Benjamin
authors: B
authors: Dieplinger
authors: Margot
authors: M
authors: Egger
authors: Christian
authors: C
authors: Gabriel
authors: Werner
authors: W
authors: Poelz
authors: Elisabeth
authors: E
authors: Morandell
authors: Beata
authors: B
authors: Seeber
authors: Florian
authors: F
authors: Kronenberg
authors: Meinhard
authors: M
authors: Haltmayer
authors: Thomas
authors: T
authors: Mueller
authors: Hans
authors: H
authors: Dieplinger
mesh_terms: D000209:Acute-Phase Proteins / Q000378:metabolism*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015415:Biomarkers / Q000097:blood; D002352:Carrier Proteins / Q000097:blood*; D004797:Enzyme-Linked Immunosorbent Assay / Q000592:standards*; D005260:Female; D006023:Glycoproteins / Q000097:blood*; D006333:Heart Failure / Q000097:blood* / Q000175:diagnosis; D006801:Humans; D008297:Male; D008875:Middle Aged; D018410:Pneumonia, Bacterial / Q000097:blood* / Q000175:diagnosis; D029424:Pulmonary Disease, Chronic Obstructive / Q000097:blood* / Q000175:diagnosis; D012016:Reference Values; D051436:Renal Insufficiency, Chronic / Q000097:blood* / Q000175:diagnosis; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D018805:Sepsis / Q000097:blood* / Q000175:diagnosis; D012709:Serum Albumin; D000075462:Serum Albumin, Human
chemical_list: C088246:AFM protein, human; D000209:Acute-Phase Proteins; D015415:Biomarkers; D002352:Carrier Proteins; D006023:Glycoproteins; D012709:Serum Albumin; D000075462:Serum Albumin, Human
keywords: B-type natriuretic peptide; BNP; C-reactive protein; CLSI; COPD; CRP; CV; Clinical and Laboratory Standards Institute; Diagnosis; ELISA; HF; IL-6; Interleukin-6; PBS; PCT; Prognosis; RCV; RT; Tumor marker; Vitamin E; chronic obstructive pulmonary disease; coefficient of variation; eGFR; enzyme-linked immunosorbent assay; estimated glomerular filtration rate; heart failure; interleukin-6; phosphate-buffered-saline; procalcitonin; reference change value; room temperature
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