Department of Internal Medicine, Södra Älvsborgs Hospital, Borås, Sweden
Department of Internal Medicine, Sahlgrenska University Hospital, Gothenburg, Sweden.
J Crohns Colitis. 2015 Jan;9(1):26-32. doi: 10.1016/j.crohns.2014.06.002.
Leukocyte-derived proteins in faeces, especially calprotectin, are increasingly used to assess disease activity in ulcerative colitis. The objectives of the present study were to assess the importance of factors related to the stool sampling procedure.
For 2 days, patients with active ulcerative colitis collected two stool samples at each bowel movement. The time of defecation, consistency and presence of blood were self-recorded in a diary. The variability in the concentrations of calprotectin during the day and between two consecutive days was assessed, as was the stability of calprotectin concentrations in samples stored at room temperature.
Altogether, 18 patients collected 287 stool samples. The intraclass correlation coefficient in pairs of samples from 132 bowel movements was 0.79 (95% CI 0.48-0.90). The median individual coefficient of variation in samples collected during the same day was 52% (4-178). There was a correlation between the level of calprotectin and the time between bowel movements (r = 0.5; p = 0.013). After 3 days at room temperature the calprotectin concentrations in stool samples were unchanged, but after 7 days a significant (p < 0.01) decrease was found (mean 28%; 95% CI 0.10-0.47).
The present data reveal a great variability in the concentrations of calprotectin in stool samples collected during a single day. Since the levels of calprotectin increased with longer time between the bowel movements, it seems most appropriate to analyse stool from the first bowel movement in the morning. Moreover, storage of stool samples at room temperature for more than 3 days is not advisable.
粪便中白细胞衍生蛋白，尤其是钙卫蛋白，越来越多地用于评估溃疡性结肠炎的疾病活动度。本研究的目的是评估与粪便采样过程相关因素的重要性。
在 2 天内，活动期溃疡性结肠炎患者每次排便时收集 2 份粪便样本。排便时间、粪便稠度和是否带血均记录在日记中。评估日间和连续 2 天钙卫蛋白浓度的变异性，以及室温下储存的粪便样本中钙卫蛋白浓度的稳定性。
共 18 例患者收集了 287 份粪便样本。132 次排便中配对样本的组内相关系数为 0.79（95%CI 0.48-0.90）。同一天采集的样本中个体变异系数中位数为 52%（4-178）。钙卫蛋白水平与排便时间之间存在相关性（r = 0.5；p = 0.013）。室温下储存 3 天后，粪便样本中的钙卫蛋白浓度没有变化，但 7 天后发现明显下降（平均 28%；95%CI 0.10-0.47）。
本研究数据显示，在一天内采集的粪便样本中，钙卫蛋白浓度存在很大的变异性。由于钙卫蛋白水平随排便时间的延长而增加，因此似乎最适合分析早晨首次排便的粪便。此外，不建议将粪便样本储存在室温下超过 3 天。
