Mycophenolate mofetil following glucocorticoid treatment in Henoch-Schonlein purpura nephritis: the role of early initiation and therapeutic drug monitoring

Background Henoch-Schonlein purpura (HSP) is the most common vasculitis in childhood and traditionally considered as a self-limiting disease. However, renal involvement can unfavorably determine long-term prognosis. The reported regimens to treat HSP nephritis (HSPN) are diverse, indicating that the most effective treatment remains controversial. Methods This retrospective, single-center study involved 18 patients presenting with HSPN and nephrotic-range proteinuria. We aimed to investigate the efficacy and safety of mycophenolate mofetil (MMF) and identify a cut-off level for estimated mycophenolic acid area under the curve (eMPA-AUC(0-12h)) values, which can predict complete remission with high sensitivity. Results Despite prior insufficient therapeutic response to corticosteroids, 89% of patients showed a significant decrease in proteinuria after 1 month of MMF treatment. None of them relapsed during treatment; however, two children relapsed after discontinuation. Based on results of a receiver operating characteristic (ROC) analysis, an eMPA-AUC(0-12h) >56.4 mg*h/l was a predictor for complete remission within 3 months (80% sensitivity, 83.3% specificity, p = 0.035). During MMF administration, we encountered no adverse event requiring discontinuation of treatment. Conclusion Our study demonstrates that MMF is a safe and potentially effective secondary treatment option for children with HSPN to achieve and maintain long-term remission without serious side effects. To achieve complete remission within 3 months, resolve severe inflammatory glomerular lesions, and avoid progression to chronic kidney disease, we propose timely diagnosis and early initiation of MMF with an eMPA-AUC0-12h value of 56.4 mg*h/l.