Systemic lupus erythematosus (SLE) is a common chronic autoimmune disease, also more common in children, called cSLE, with an incidence of 0.3-0.9 cases per 100,000 people. Mycophenolate mofetil (MMF), a commonly used drug for the treatment of cSLE, is converted in vivo to mycophenolic acid (MPA) in the active state, which inhibits the rate-limiting enzyme, inosine monophosphate dehydrogenase, and thus inhibits the pathway for the de novo synthesis of purines in T- and B-lymphocytes.

In order to obtain better clinical outcomes, clinical trials have been conducted to explore MPA concentration targets using therapeutic drug monitoring (TDM). However, the occurrence of complications during the treatment of cSLE has been a major clinical concern, especially the morbidity and mortality associated with renal injury, which is more common in children than in adults. Therefore, there is a need to investigate the relationship between MPA exposure levels and comorbidities.