title: Determination of cerebrospinal fluid cystatin C on Architect ci8200.
abstract: BACKGROUND
  Human cystatin C is a cysteine protease inhibitor produced by all nucleated cells in the body and the protein is present in all body fluids. The concentration in cerebrospinal fluid (CSF) is considerably higher than in plasma. Cystatin C levels seem to influence the development of Alzheimer disease (AD) and low levels in the brain are associated with an increased risk for AD. The aim of this study was to develop a high throughput assay for the quantification of cystatin C in CSF.
  
  
  METHODS
  Antigen excess, imprecision, interference, linearity, recovery, sample stability and reference values were evaluated on Architect ci8200 (Abbott Laboratories, Abbott Park, IL, USA).
  
  
  RESULTS
  The assay had an antigen-excess limit at 23 mg/L and was linear over the range of 0.84 to 8.33 mg/L. Results > 8.33 mg/L were automatically rerun in a higher dilution. Within-run coefficient of variation (CV) was 1.71, 1.10 and 0.79%, between day CV was 1.71, 0.39 and 1.45%, between-run CV was 0.58, 0.66 and 0.48%, and total CV was 2.49, 1.34 and 1.72% at cystatin C concentrations of 1.39, 3.17 and 6.28 mg/L, respectively. The recovery was 97-102%. No interference at a 7.5% deviation level was observed for 8.5 g/L of hemoglobin or 800 mg/L (1368 micromol/L) of bilirubin. Reference values for cystatin C in cerebrospinal fluid obtained with this method were 2.42-14.33 mg/L.
authors.affiliation: Department of Clinical Chemistry and Pharmacology, University Hospital, Uppsala, Sweden.
authors.forename: Annaby Moussa
authors.initials: AM
authors.lastname: Ndjole
authors.forename: Constantin
authors.initials: C
authors.lastname: Bodolea
authors.forename: Tom
authors.initials: T
authors.lastname: Nilsen
authors.forename: Torsten
authors.initials: T
authors.lastname: Gordh
authors.forename: Mats
authors.initials: M
authors.lastname: Flodin
authors.forename: Anders
authors.initials: A
authors.lastname: Larsson
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000175:diagnosis* / Q000503:physiopathology; D003199:Computer Systems / Q000706:statistics & numerical data*; D055316:Cystatin C / Q000134:cerebrospinal fluid*; D004797:Enzyme-Linked Immunosorbent Assay / Q000295:instrumentation / Q000379:methods; D005260:Female; D057166:High-Throughput Screening Assays; D006801:Humans; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D012016:Reference Values; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted / Q000295:instrumentation*; D054928:Validation Studies as Topic
chemical_list: D055316:Cystatin C