Elia calprotectin 2 assay

Calprotectin concentrations in heparin plasma and saliva samples were measured using a particle-enhanced turbidimetric immunoassay (Gentian Diagnostics AS, Moss, Norway) on a Cobas c501 analyzer (Roche Diagnostics GmbH, Mannheim, Germany). Measurements were conducted according to the manufacturer's instructions. Salivary CP concentrations in healthy controls were measured immediately after collection and after storage of a sample at -20 °C to investigate the potential effect of a freeze-thaw cycle. Fecal CP concentrations were determined using the EliA Calprotectin 2 assay (Phadia GmbH, Freiburg, Germany), a fluorescence enzyme immunoassay, on the Phadia 250 (Thermo Fisher Scientific, Uppsala, Sweden) according to the manufacturer's instructions.

The medical records of patients with CD were retrospectively reviewed across two tertiary referral centres. Data were collated from The Royal Hospital for Sick Children, Edinburgh Within the RHSC cohort the CRP was analysed on an Abbott Architect c16000 using an immunoturbometric assay (Abbott, Abbott Park, Illinois, USA) and FC on the CALP0170Calprotectin (ALP) ELISA (Lysaker, Norway). The RCH FC analysis was performed on the Phadia 250 instrument using the EliA Calprotectin 2 assay (Phadia GmbH, Freiburg, Germany) and CRP on the Vitros systems 250/350/950/5/5600/4600 (Ortho-clinical diagnostics, High Wycombe, UK) .