Serum Procollagen III Propeptide Is Not of Diagnostic Predictive Value in Collagenous Colitis

SUMMARY: : The thickened collagen layer found subepithelially in colorectal biopsies from patients with collagenous colitis consists partly of collagen type III. Procollagen III propeptide (P-III-NP) is a product of collagen III metabolism. We analyzed serum levels of this propeptide to assess its diagnostic value in collagenous colitis. Serum from 38 patients with collagenous colitis and 38 age- and sex-matched controls were analyzed for P-III-NP. Data on the patients included duration and severity of symptoms, treatment, and thickness of the collagen layer. There was no significant difference between P-III-NP in patients (3.8 ± 2.0 μg/L) and controls (3.7 ± 1.3 μg/L), and P-III-NP did not correlate with clinical activity. There was a significant correlation, however, between P-III-NP and age both in patients (r = 0.57, p = 0.0009) and controls (r = 0.64, p = 0.0001). This study shows that P-III-NP is not useful as a diagnostic or prognostic tool in collagenous colitis, and a colonoscopy with biopsy is still the only diagnostic method available.