5-Aminosalicylates and Renal Function in Children with Inflammatory Bowel Disease

Introduction: drugs containing 5-ASA (aminosalicylates) are widely used in the management of inflammatory bowel disease (IBD) both for treating the active phases and maintaining remission. The use of these agents has been associated with the risk of developing a tubuleinterstitial nephritis although the presence of this injury in IBD patients (pts) who had never received 5-ASA has been reported. There are no studies on the renal function of children with IBD receiving 5-ASA Aim: in a group of children with IBD on 5-ASA therapy we have assessed the renal function and its relationship to the cumulative dose of 5-ASA, disease duration and activity indexes (PCDAI for CD, PUCAI for UC). Methods: We enrolled 23 consecutive children (10 female) (mean age [SD]: 10.0 [5.6] years) with ulcerative colitis (UC), and 13 children (7 female) (mean age [SD]: 12.0 [4.3] years) with Crohn's disease (CD). All were referred to our Department with a diagnosis of IBD for re-evaluation of their condition. All were receiving only 5-ASA. Renal function test was performed by obtaining a 24-hour urine collection and a blood sample drawn at the end of the urine collection. Glomerular filtration rate, fractional excretion of sodium, tubular reabsorption of phosphate and proteinuria were measured. The total drug dose, the total drug dose/kg and the total drug dose/kg/month of therapy were also calculated. Pts were subdivided in two groups on the basis of the proteinuria level, <150mg/die (group A), >150mg/die (group B): the latter were compared for renal function, drug dose, and disease duration. Difference between groups was analyzed with non-parametric test (Wilcoxon test) (p <0.05 considered as significant). Results: 9 UC pts and 8 CD pts exhibited an abnormal proteinuria (>150 mg/ die). A and B groups did not differ for renal function parameters, total drug dose taken, total drug dose/kg and the total drug dose/kg/month of therapy. The disease duration (months) was significantly shorter in children with a proteinuria >150mg/die (CD; A: 48.5±53.6, B: 20.1±9.6 - UC; A: 31.3±33.4, B: 20.2±31.1). The level of proteinuria significantly correlated with the acitivity of disease both for CD (r: 0.77, p<0.01) and for UC (r:0.69, p<0.01). Conclusions: in children with IBD chronic 5-ASA administration does not cause proteinuria; the latter appears to be related to the disease activity. It is suggested that proteinuria can be a feature of extra-intestinal involvement of IBD.