Improved localizing method of radiopill in measurement of entire gastrointestinal pH profiles: colonic luminal pH in normal subjects and patients with Crohn's disease.

OBJECTIVE

To measure gastrointestinal (GI) pH profiles in patients with Crohn's disease with an improved pH radiotelemetry method.

METHODS

A computer-assisted method was developed to exactly localize a pH sensitive radiotelemetry capsule (radiopill) in the GI tract from the stomach to the cecum by detecting distinct changes in transmitted pH signals sampled at 1-sec intervals. The combined usage of a radiodirectional probe facilitated localization of the radiopill in the colon. With this improved method, GI pH profiles in four patients (male/female, 3/1; age range, 21-34 yr) with Crohn's disease that involved the left colon (active disease: 3; disease at quiescent state, 1) were measured and compared with those in four gender- and age-matched control subjects (controls).

RESULTS

Gastric and small intestinal luminal pH profiles in Crohn's disease were similar to those in the controls. In contrast, colonic luminal pH profiles in both right (uninvolved) and left (involved) colon in active or quiescent Crohn's disease showed more coarse fluctuations with a significantly low value than those seen in the controls. The minimum colonic pH registered in the four patients was 0.6, 1.2, 3.2, and 5.3 pH unit, respectively. The overall mean luminal pH (+/-SD) in the right colon was 5.3 +/- 0.3 for the patients versus 6.8 +/- 0.2 for the controls (p < 0.01) and that in the left colon was 5.3 +/- 0.7 versus 7.2 +/- 0.3 (p < 0.01), respectively.

CONCLUSION

This study first demonstrates that an extremely acidic colonic environment occurs in either active or inactive Crohn's disease.