The European League Against Rheumatism (EULAR) and the European Society of Nephrology-European Dialysis and Transplantation Association (ERA-EDTA) jointly published a new edition of guidelines in the Annals of Rheumatology on July 31, recommending renal biopsy to guide the treatment of lupus nephritis in adults and children to achieve the goal of complete renal response. The new edition of the guidelines recommends renal biopsy in patients with any sign of renal involvement (especially in patients with recurrent proteinuria ≥0.5 g/24 h, especially in the presence of glomerular hematuria and/or cytubular pattern). Because of the potentially aggressive nature of lupus nephritis, the threshold for renal biopsy should be lowered and considered in patients with persistent isolated glomerular hematuria, isolated leukocyturia (after excluding other causes such as infection or drugs), and rare unexplained renal insufficiency with normal urinalysis findings. Biopsy should be performed within 1 month of onset, preferably before immunosuppressive therapy. However, if biopsy cannot be performed promptly, high-dose glucocorticoid therapy should not be postponed. The goal of immunosuppressive therapy should be complete response, defined as a urine protein/creatinine ratio <50 mg/mmol, which is approximately equivalent to proteinuria <0.5 g/24 h. The ultimate goals of therapy are long-term protection of renal function, prevention of acute exacerbations, avoidance of treatment-related damage, and improvement of quality of life and survival. Treatment selection must be based on a decision mutually agreed upon by the physician and patient. In types I and VI lupus nephritis, immunosuppressive therapy is usually not required unless additional renal lupus activity is present. In adults, for most cases of type III-IV lupus nephritis, initial therapy is recommended with mycophenolate (target dose 3 g/d for 6 months) or an equivalent dose of enteral mycophenolate sodium, or low-dose intravenous cyclophosphamide (total dose 3 g over 3 months) combined with oral glucocorticoids (0.5 mg/kg・d). To improve efficacy, initial therapy should be combined with 3 sequential shocks of intravenous methylprednisolone 500-750 mg followed by oral prednisone 0.5 mg/kg・d (for 4 weeks), with this dose being reduced to ≤10 mg/d at 4-6 months. for patients with simple type V lupus nephritis with combined nephrotic range proteinuria, mycophenolate mofetil (target dose 3 g/d for for 6 months) in combination with oral prednisone 0.5 mg/kg・d for treatment. Lupus nephritis in children tends to become more severe as the damage accumulates, and treatment and monitoring recommendations for lupus nephritis in children are similar to those for adults. For the best long-term prognosis, treatment regimens should include a plan for a smooth transition to an adult patient specialist. The new version of the guidelines also includes: ・Adjunctive therapy. For example, angiotensin-converting enzyme inhibitors (ACEI) or angiotensin receptor blockers (ARB) are recommended for patients with combined proteinuria or hypertension. Hydroxychloroquine is recommended to reduce nephrogenic relapses and limit the accumulation of renal and cardiovascular damage, thereby improving prognosis. ・Monitoring and prognosis of lupus nephritis. Follow-up every 2 to 4 weeks for 2 to 4 months after diagnosis is recommended. In addition, repeat biopsies are recommended for some patients (e.g., those with relapses). ・Treatment of end-stage renal disease in patients with lupus nephritis. The new version of the guidelines states that all types of renal replacement therapy can be used in patients with lupus, and transplantation can be performed when there is no lupus activity for 3 to 6 consecutive months or when lupus activity is at a low level. ・Antiphospholipid syndrome-associated nephropathy. Hydroxychloroquine and/or antiplatelet/anticoagulation therapy should be considered. ・Lupus nephritis during pregnancy. Hydroxychloroquine may be used, and low-dose prednisone, azathioprine, and/or calcineurin inhibitors may be used if necessary. Acetylsalicylic acid should be considered to reduce the risk of preeclampsia. These recommendations are important given that half of the patients with SLE will develop lupus nephritis, which in turn increases the risk of renal failure, cardiovascular disease, and death.