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I read with great interest the article by Haisma et al. that reports on fecal calprotectin instability.(1) The authors are to be commended on their study. However, some points deserve comment.
The authors tested the stability of calprotectin after the stool was homogenized. The clinical relevance of this is unclear since what is important is the stability of calprotectin in stool after collection and before analysis. The studies that have evaluated fecal calprotectin stability in this situation are in alignment; calprotectin is stable in unprocessed stool at room temperature for at least 3 days with some studies suggesting up to a week (for review see D’Amico et al.).(2)
No support is provided for the statement by Haisma et al. that calprotectin instability in stool samples sent by mail may lead to errors in treat-to-target strategies. Indeed, the literature says otherwise.
1. Haisma SM, van Rheenen PF, Wagenmakers L, Muller Kobold A. Calprotectin instability may lead to undertreatment in children with IBD. Arch Dis Child. 2020;105:996-8 doi: 10.1136/archdischild-2018-316584 [published Online First: 2019/01/19].
2. D'Amico F, Rubin DT, Kotze PG, et al. International consensus on methodological issues in standardization of fecal calprotectin measurement in inflammatory bowel diseases. United European Gastroenterol J. 2021;9:451-60 doi: 10.1002/ueg2.12069 [published Online First: 2021/05/08].