Assessment of ileal pouch inflammation by single-stool calprotectin assay

PURPOSE: Assessment of inflammation within the ileal pouch to establish a d iagnosis of "pouchitis" requires both pouch endoscopy and biopsy because th ere can be a poor correlation between macroscopic and histologic assessment s of inflammation. A simplified diagnostic test would be of clinical advant age. Calprotectin is a stable myelomonocytic protein, measurable in feces. It quantitatively relates to inflammation within the gastrointestinal tract . This study was designed to compare single and 24-hour stool measurements of calprotectin in patients with and without evidence of ileal pouch inflam mation with endoscopic, histologic, and immunohistochemical indices. METHOD S: Twenty-four-hour stool collections were made in ileal pouch patients, 9 with and 15 without (7 with ulcerative colitis and 8 with familial polyposi s coil) evidence of pouch inflammation. First-morning stool concentration a nd total 24-hour calprotectin were quantified by use of a single step enzym e-linked immunosorbent assay. Biopsies from the reservoir were taken for co nventional histology and scoring of intraepithelial neutrophil infiltrate. Cells positive for CD3, CD45RO, CD14, and CD15 within the lamina propria we re quantified by use of immunohistochemistry. RESULTS: The mean first-morni ng stool calprotectin concentration correlated with the 24-hour level (r = 0.91; P = <0.0001). The median single-stool calprotectin concentrations wer e 39 mg/l, 4 mg/l, and 8.5 mg/l (normal range, 0.2-10 mg/l) in patients wit h inflamed, noninflamed ulcerative colitis, and familial adenomatous polypo sis, respectively. All nine patients with endoscopic and histologic evidenc e of pouch inflammation had raised stool calprotectin. Two of 15 patients w ithout evidence of pouch inflammation had abnormal stool calprotectin. Sing le-stool calprotectin concentration correlated with the percentage of matur e granulocytes (CD15; r = 0.46; P = 0.04) and activated macrophages (CD14; r = 0.65; P = 0.006), but not memory T cells (CD45RO; r = -0.05; P = 0.4) w ithin the lamina propria. CONCLUSION: Single first-morning stool calprotect in levels provide a quantitative measure of pouch inflammation, which may b e helpful in the diagnosis and assessment of pouchitis.