Reference Intervals for Fecal Calprotectin in Adults Using Two Different Extraction Methods in the Uppsala-SCAPIS Cohort.

Background: Fecal calprotectin measurement is generally recommended to exclude inflammatory bowel disease (IBD) in patients with suspected IBD. A problem with the fecal calprotectin assays so far has been the rather long test-turnaround times. Recently a particle enhanced turbidimetric immunoassay (PETIA) for fecal calprotectin with assay times of approximately 10 minutes has been introduced on the European market. The aim of this study was to define reference intervals for adults with this new fecal calprotectin PETIA using two different extraction methods.

Methods: Samples were collected from 382 healthy individuals from the Swedish CArdioPulmonary bioImage Study (SCAPIS) Uppsala cohort in the age range 50 - 65 years. 202 samples were processed with CALEX® Cap extraction device (BÜHLMANN, Schönenbuch, Switzerland) and 180 samples were extracted using weighed samples. The extracted samples were analyzed on a Mindray BS-380 using the fCal Turbo PETIA reagent (BÜHLMANN).

Results: The calculated reference values for the Calex device were < 199 µg/g for the whole cohort, < 184 µg/g for females, and < 215 µg/g for males, while the corresponding values for weighed samples were < 153 µg/g for the whole cohort, < 141 µg/g for females, and < 215 µg/g for males. There were no significant statistical differences for calprotectin levels in males and females.

Conclusions: The CALEX device yielded slightly higher calprotectin values. As there were no significant gender differences, the study indicates gender independent reference intervals of < 199 µg/g feces for the CALEX device and < 153 µg/g feces for weighed samples in patients in the 50 - 65 year age range.