Between-assay variability of faecal calprotectin enzyme-linked immunosorbent assay kits

Ann Clin Biochem. 2013 Jan;50(Pt 1):53-61. doi: 10.1258/acb.2012.011272. Epub 2012 Nov 5.


Background: Faecal calprotectin (f-Cp), a marker of intestinal inflammation, can be used to distinguish between functional and organic bowel disease. F-Cp, following extraction, is commonly quantified using enzyme-linked immunosorbent assays (ELISAs) but there are no data comparing the different f-Cp assays or sample extraction devices. We, therefore, evaluated and compared the performance of the Immunodiagnostik, Bühlmann and Eurospital f-Cp ELISA assays as well as the Roche, Immunodiagnostik and ScheBo Biotech commercial faecal extraction devices. We also briefly report results from a pilot f-Cp external quality assurance (EQA) scheme.

Methods: Imprecision, linearity, recovery, drift and limit of quantitation of the f-Cp assays were evaluated and between-assay variability assessed. The three commercial sample extraction devices were compared with the manual weighing method. Four faecal samples were distributed as part of a pilot EQA scheme to 15 laboratories using quantitative ELISA f-Cp assays.

Results: The three f-Cp assays demonstrated adequate intra-/interbatch imprecision, linearity and recovery. The cross-comparison study and EQA data demonstrated that, for the same sample, the Bühlmann assay reports up to 3.8 times higher f-Cp concentrations than the Immunodiagnostik and Eurospital assays. On average, the commercial extraction devices led to a 7.8-28.1% under-recovery of f-Cp in comparison to the manual weighing method.

Conclusions: Laboratories should be aware of the lack of the assay standardization, as demonstrated by the between-assay variability. A comparison between f-Cp concentrations reported by these assays and clinical markers of disease severity is required in order to determine their diagnostic accuracy. The EQA scheme represents the first available programme for f-Cp.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Biomarkers / analysis
  • Calibration
  • Enzyme-Linked Immunosorbent Assay / methods
  • Enzyme-Linked Immunosorbent Assay / standards*
  • Feces / chemistry*
  • Humans
  • Inflammatory Bowel Diseases / diagnosis*
  • Inflammatory Bowel Diseases / immunology
  • Leukocyte L1 Antigen Complex / analysis*
  • Leukocyte L1 Antigen Complex / immunology
  • Limit of Detection
  • Quality Control
  • Reproducibility of Results


  • Biomarkers
  • Leukocyte L1 Antigen Complex