[Lupus nephritis: from diagnosis to treatment]

Renal involvement in systemic lupus erythematosus (SLE), so-called lupus nephritis (LN), is one of the most frequent organ manifestations with an incidence of approximately 40-60%. It is not uncommon for renal involvement to be the initial manifestation of SLE or to occur in the first 5-10 years after diagnosis of SLE. Urinalysis is useful in screening for the presence of LN, demonstrating proteinuria or active sediment with acanthocytes. Histologic confirmation of LN, and thus the LN class present, is currently the gold standard for confirming the diagnosis. In addition, knowledge of the LN class is a relevant component of adequate treatment planning in SLE patients with LN. In particular, early diagnosis and rapid response to therapy are of prognostic importance for the preservation of renal function as well as morbidity and mortality of the mostly young patients at the time of initial diagnosis. Thus, the focus of therapy is to achieve complete remission, as well as to avoid active disease phases. Due to a complex pathogenesis and at the same time a very heterogeneous clinical presentation, with six different histological classes of LN, there are different therapeutic targets. This in turn results in a significant expansion of the study landscape in the field of LN with an increasing understanding of the signaling pathways and influencing factors, and fortunately in a growing armamentarium of available targeted therapy options. Simultaneously, new insights into drug therapy to inhibit progression of chronic renal disease are opening up supportive therapy options that can further improve preservation of renal function.