Inclusion Criteria:  Patients aged 18 to 60 years Patients with chronic inflammatory bowel disease, IBD (Crohn's or Ulcerative colitis) Patients with active or inactive disease (remission) Patients treated as part of their routine care and required to undergo a routine blood test, fecal tests and endoscopic examination, if applicable Patients covered by the social security scheme and / or professional health insurance Patients giving their free and informed consent after information  Exclusion criteria :  Patients who have been deemed unfit to participate in the study by the attending physician Patients under 18 years Patients who have undergone colorectal surgery with complete resection or who have undergone intestinal resection surgery within six months Patients taking irritating laxatives, nonsteroidal anti-inflammatory drugs (NSAIDs) and drug formulations containing prostaglandins at the time of urine collection