Time-resolved fluorimetric immunoassay of calprotectin: technical and clinical aspects in diagnosis of inflammatory bowel diseases.
BACKGROUND
Growing evidence in the literature shows the clinical importance of the calprotectin assay in faeces, especially for the differential diagnosis and monitoring of patients with inflammatory bowel diseases.


METHODS
We developed a time-resolved fluorimetric immunoassay for calprotectin to extend the limited measuring range of the commercially available ELISA method currently used in our laboratory. Together with the introduction of a non-enzymatic label, this new method offers the advantages of better precision and higher sensitivity.


RESULTS
The new assay shows a dynamic measuring range extended by a factor four, which reduces the number of samples with concentrations outside the measuring range from 30% to only 4%. The value of the assay was confirmed in various patient groups suffering from active and inactive gastrointestinal diseases. We suggest that the frequent coincidence of a high calprotectin concentration with intestinal blood loss is not the consequence of mere blood loss, but can be ascribed to neutrophil infiltration and subsequent shedding into the intestinal lumen as a result of intestinal inflammation or malignancy.


CONCLUSIONS
We expect that in the near future faecal calprotectin will be used as a non-invasive routine diagnostic marker and an effective laboratory parameter to monitor patients with inflammatory bowel disease.
van der Sluijs Veer
Gertjan
G
Department of Clinical Chemistry, Medisch Spectrum Twente Hospital, Enschede, The Netherlands. g.vandersluijsveer@ziekenhuis-mst.nl
van den Hoven
Barbara
B
Russel
Maurice G V M
MG
van den Bergh
Frank A J T M
FA
D000328:Adult; D015415:Biomarkers / Q000032:analysis / Q000097:blood; D003424:Crohn Disease / Q000175:diagnosis; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D005470:Fluorometry / Q000379:methods; D005767:Gastrointestinal Diseases / Q000175:diagnosis; D006801:Humans; D007118:Immunoassay / Q000379:methods; D015212:Inflammatory Bowel Diseases / Q000097:blood / Q000175:diagnosis*; D007414:Intestinal Neoplasms / Q000175:diagnosis; D039841:Leukocyte L1 Antigen Complex / Q000097:blood*; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013997:Time Factors
D015415:Biomarkers; D039841:Leukocyte L1 Antigen Complex