P791 Up to one third of rapid thiopurine-S-methyltransferase metabolizers manifest clinical and/or laboratory azathioprine side effects: A single centre experience

Abstract Background According to ECCO-ESPGHAN consensus guidelines, azathioprine (AZA) can be used for maintenance of remission in paediatric Inflammatory Bowel Disease (IBD). AZA side effects are well documented. Haematological toxicity affects 2-14% patients and pancreatitis up 7% them, requiring modification dosage or its cessation. Thiopurine-S-methyltransferase (TPMT) activity should tested prior commencement. Slow metabolizers not started on intermediate ones get a dose reduction. This study evaluates the incidence TPMT rapid metabolizers. Methods Retrospective evaluation prospectively collected data children who received between 3/13 10/22. Focusing both clinical laboratory Results Ninety had tested. Only 1 slow metabolizer were identified. All diagnosed with IBD, 62 (70,5%) Crohn’s (CD), 16 (18,2%) Ulcerative Colitis (UC), 7 Very Early Onset IBD (VEO-IBD) undifferentiated. Forty-seven male (53,4%) 41 female. The median age at diagnosis was 13.5±3,9 years. Of 88 metabolizers, 82 (93%) AZA. remaining 6 different treatment strategies. Clinical and/or documented 27 cases (32,9%). most frequent affecting 19 participants (23.1%). In 13 (68,4%) leukopenia resolved spontaneously, 4 (21%) reduction required, 3 (15,8%) stopped. Pancreatitis identified (7,3%). Half discovered by findings remainder correlate. 2 cases, normalized follow-up examination, withdrawn. intolerance found twice, once split dosage, manifested average within 10,9 months since start (0.5-43 months), 0,54 one case manifesting after 79 treatment. this single case, autoimmune is debated. appeared days from Boys slightly more frequently (15/27, 55%). CD (16/27, 59%). However, common cohort. Conclusion Being reduce risk effects. these demonstrate 32,9% occurrence emphasising importance