Department of Clinical Biochemistry, Aarhus University Hospital, Aarhus, Denmark.
Scand J Clin Lab Invest. 2022 Sep;82(5):349-355. doi: 10.1080/00365513.2022.2092901. Epub 2022 Jul 13.
As an activation product of neutrophil granulocytes, calprotectin has been widely used in fecal samples for diagnosis and monitoring of patients with inflammatory bowel disease. However, fecal sample collection is cumbersome, and pre-analytical sources of error are plentiful. Therefore, plasma calprotectin is being investigated as a promising new biomarker. To utilize any biomarker, pre-analytical factors such as stability and susceptibility to interference from hemolysis must be established. We present precision estimates, stability results as well as interference study on plasma calprotectin in EDTA-plasma using the Thermo Fischer Phadia 250 EliA Calprotectin immunoassay. Precision was estimated by the use of patient pools as well as internal quality controls provided by the manufacturer. Coefficients of variance were below 6.9% for patient samples. Calprotectin was stable in EDTA plasma after storage at 5-8 °C for up to 4 days, as well as after long-term storage at -20 °C. Susceptibility to interference from hemolysis was high, especially for low concentrations of calprotectin (<50 ng/mL) where hemoglobin levels above 0.02 mmol/L lead to false increase in calprotectin concentrations of up to 100%.
作为中性粒细胞的激活产物，钙卫蛋白已广泛应用于粪便样本，用于诊断和监测炎症性肠病患者。然而，粪便样本的采集较为繁琐，且分析前存在较多的误差来源。因此，血浆钙卫蛋白作为一种很有前途的新型生物标志物正受到研究关注。要利用任何生物标志物，都必须确定其分析前因素，如稳定性和对溶血干扰的敏感性。我们使用 Thermo Fischer Phadia 250 EliA Calprotectin 免疫分析法，对 EDTA 血浆中的钙卫蛋白进行了精密度估计、稳定性研究和干扰研究。使用患者样本和制造商提供的内部质量控制品来评估精密度。患者样本的变异系数低于 6.9%。钙卫蛋白在 EDTA 血浆中 5-8°C 下储存长达 4 天以及在-20°C 下长期储存均稳定。对溶血干扰的敏感性很高，特别是对钙卫蛋白浓度较低（<50ng/mL）的样本，血红蛋白水平超过 0.02mmol/L 时，钙卫蛋白浓度会错误升高高达 100%。
