Background Treatment decisions in children with inflammatory bowel disease (IBD) are increasingly based on longitudinal tracking of faecal calprotectin concentrations, but there is little known about the stability of this protein in stool.
Methods We stored aliquots of homogenised stool at room temperature and at 4°C, and measured the calprotectin concentration for 6 consecutive days with three different assays. In addition, we assessed calprotectin stability in assay-specific extraction buffers kept at room temperature.
Results After 6 days of storage at room temperature, mean percentage change from baseline calprotectin concentrations in stool and extraction buffer was 35% and 46%, respectively. The stability of calprotectin was significantly better preserved in samples stored at 4°C (p=0.0066 and 0.0011, respectively).
Conclusions Calprotectin is not stable at room temperature. Children with IBD and their caretakers may be falsely reassured by low calprotectin values. The best advisable standard for preanalytical calprotectin handling is refrigeration of the stool sample until delivery at the hospital laboratory.
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Contributors All authors contributed to the study concept and design. LW collected the data and analysed the data together with SMH, AMK and PFvR. SMH and PFvR drafted the first version of the research letter.
Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests PFvR received funding from BÜHLMANN Laboratories for other projects.
Patient consent Not required.
Provenance and peer review Not commissioned; externally peer reviewed.
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