Circulating calprotectin as biomarker in neutrophil-related inflammation: Pre-analytical recommendations and reference values according to sample type

• Circulating calprotectin is a promising biomarker for neutrophil-related inflammation. Reference values circulating differ in serum, heparin, EDTA and citrate sample tubes. Calprotectin two times higher serum compared to plasma. Storage time, temperature time centrifugation have an impact on levels. Delay of > 2 h significantly increases samples. (CLP) the evaluation Our aim was establish reference CLP different types study effect pre-analytical variables. were determined 100 healthy individuals. Pre-analytical variables evaluated 10 controls four rheumatoid arthritis patients with active disease covered type (serum with/without gel separator, plasma), pre-centrifugation (<2 h, 6 24 h), storage condition (2–8 °C, 18–25 30 °C) (24 72 7 days). measurements performed EliA™Calprotectin assay Phadia™200 (Thermo Fisher Scientific). In controls, baseline concentrations more than double concentration plasma (0.909 µg/mL versus 0.259 0.261 respectively). Heparin, stabilized up before centrifugation, whereas significant levels observed when left untreated during that period. Clinical studies need apply type-specific decision limits. To obtain reproducible results stringent handling instructions are needed.