Establishing a pediatric reference interval for plasma calprotectin

Abstract

Plasma calprotectin is a promising new biomarker of inflammatory activity and has been found to correlate well with clinical and endoscopic activity in children and adolescents with inflammatory bowel disease. A pediatric reference interval for plasma calprotectin has not been established for the Phadia 250 EliA™ Calprotectin fluoroenzyme immunoassay. In studies regarding pre-analytical properties, excellent precision and stability was found. However, sensitivity to hemolysis was demonstrated. We identified pediatric blood samples from apparently healthy children who were referred by their general practitioner for blood sampling including measurement of hemoglobin (Hb) and C-reactive protein (CRP). We excluded samples from children who had undergone additional blood sampling within 2 months before or after the index sample, if Hb was outside of local reference ranges or CRP levels were above the lower limit of the measuring interval (LLM), and any samples with a hemolysis above 0.02 mmol/L. Using this algorithm, we identified 141 blood samples. No outliers were identified. We established the following reference intervals according to CLSI C28-A3 using non-parametric statistics: 1–17 years: 16–246 µg/L. Our results may prove useful for further utilization of plasma calprotectin as a marker of inflammation in children and adolescents with inflammatory disorders.

Keywords:

• Calprotectin
• plasma
• pediatrics
• reference values
• inflammation

Acknowledgements

The authors acknowledge the invaluable contributions by Charlotte Nørby Pedersen, Christian Gundesen and laboratory technicians Laura Højbak Munk, Peter Skouboe and Gitte Paulsen.

Disclosure statement

ABB has received speaker fees from Thermo Fisher Scientific. The authors report no conflicts of interest.

Additional information

Funding

This study was supported by the Department of Clinical Biochemistry, Aarhus University Hospital, Central Denmark Region. Thermo Fisher Scientific provided calprotectin kits free of charge for this study (Agreement No. 2021-731-16070).