Significant Increase in Prostaglandin E-Main Urinary Metabolite by Laxative Administration: Comparison with Ulcerative Colitis

<i>Objective:</i> To assess the production of prostaglandin E₂, an important chemical mediator in diarrhea induced by laxative administration, a prostaglandin E-main urinary metabolite (7α-hydroxy-5,11-diketotetranor-prosta-1,16-dioic acid, PGE-MUM) was measured in healthy volunteers and compared with the values of patients with ulcerative colitis. <i>Methods:</i> PGE-MUM was determined by a simplified immunoassay of bicyclic PGE-MUM and analyzed for the influence of laxative administration and active/remission phases of ulcerative colitis. <i>Results:</i> Administration of laxatives induced a significant increase in PGE-MUM in healthy volunteers. A significant elevation was also found in the active as compared with the remission phase of ulcerative colitis. The PGE-MUM levels were significantly correlated with our modified Talstad scores, clinical disease activity indices in ulcerative colitis. It was confirmed by time course studies of individual patients that changes in PGE-MUM correlated well with colitis activity. <i>Conclusion:</i> Laxative administration induces production of prostaglandin E₂ as one of the chemical mediators, although its production grade is relatively low as compared with ulcerative colitis in the active phase.