Dramatic Changes in Thiopurine Metabolite Levels in a Patient With Inflammatory Bowel Disease Treated With Tirzepatide for Weight Loss.

Thiopurines can be used to maintain remission in patients with inflammatory bowel disease. Thiopurines require regular blood count monitoring and, in specific patients, thiopurine metabolites for assessment of optimization and safety. We present the case of a 42-year-old woman with ulcerative colitis postcolectomy and ileal pouch-anal anastomosis with subsequent antibiotic-resistant diffuse pouchitis and prepouch ileitis. She was in stable remission with thiopurine monotherapy. Following tirzepatide initiation, she experienced elevated liver enzymes associated with a significant increase in thiopurine metabolite levels. This case underlines the importance of monitoring metabolite levels in patients with inflammatory bowel disease initiated on glucagon-like peptide 1-targeted therapies.