Original scientific paper

https://doi.org/10.11613/BM.2019.010707

Faecal calprotectin determination: impact of preanalytical sample treatment and stool consistency on within- and between-method variability

Gordana Juricic orcid.org/0000-0002-1937-8578 ; Department of Laboratory Diagnostics, General Hospital Pula, Pula, Croatia
Tina Brencic ; Department of Laboratory Diagnostics, General Hospital Pula, Pula, Croatia
Andrea Tesija Kuna ; Department of Clinical Chemistry, Sestre milosrdnice University Hospital Center, Zagreb, Croatia
Milena Njegovan ; Department of Clinical Chemistry, Sestre milosrdnice University Hospital Center, Zagreb, Croatia
Lorena Honovic ; Department of Laboratory Diagnostics, General Hospital Pula, Pula, Croatia

Abstract

Introduction: We assessed the differences in faecal calprotectin (FC) concentrations measured by two assays depending on the stool consistency
and extraction method.
Materials and methods: Stool samples were extracted using the EliA Stool Extraction Kit, Calex® Cap extraction device and respective weighing
methods, while FC concentrations were measured using the EliATM Calprotectin and Bühlmann fCAL® Turbo method and checked for within- and
between-method variability with regard to extraction method and stool consistency category. Extraction yield was evaluated for impact of different
sample incubation time (10 min and 1 h) in extraction buffer for both methods and for impact of different initial sample dilutions (1:50, 1:100, 1:500)
for fCAL® Turbo method.
Results: Results determined from Calex® Cap extracts were higher compared to weighing method extracts (mean bias 33.3%; P < 0.001), while
no significant difference was found between results obtained with EliA Stool Extraction Kit and weighing method (mean bias 0.1%; P = 0.484), in
both cases irrespective of stool consistency. Bühlmann fCAL® Turbo results were higher than EliATM Calprotectin results (mean bias 32.3%, P = 0.025
weighing method; and mean bias 53.9%, P < 0.001 extraction devices), the difference is dependent on stool consistency and FC concentration. Significantly
higher FC extraction yield was obtained with longer sample incubation time for both methods (P = 0.019 EliATM Calprotectin; P < 0.001
fCAL® Turbo) and with increasing initial sample dilution for fCAL® Turbo method (P < 0.001).
Conclusion: Preanalytical stool sample handling proved to be a crucial factor contributing to within- and between-FC assay variability. Standardization
is urgently needed in order to assure comparable and reliable FC results.

Keywords

calprotectin; preanalytical phase; inflammatory bowel disease; immunoassay

Hrčak ID:

217219

URI

https://hrcak.srce.hr/217219

Publication date:

15.2.2019.

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