Systemic Lupus Erythematosus: Renal Involvement

Key points

• Lupus nephritis is a major renal manifestation of systemic lupus erythematosus and can cause progressive CKD and kidney failure.
• Class I = minimal mesangial lupus nephritis: glomeruli may appear normal by light microscopy, but mesangial immune deposits are present on immunofluorescence/electron microscopy.
• Class II = mesangial proliferative lupus nephritis.
• Class III = focal lupus nephritis with active or chronic lesions involving <50% of glomeruli.
• Class IV = diffuse lupus nephritis with active or chronic lesions involving ≥50% of glomeruli.
• MRCP discriminator: class III/IV = proliferative lupus nephritis; class V = membranous pattern. Kidney biopsy class determines treatment.
• Current update: KDIGO 2024 includes mycophenolate or low-dose cyclophosphamide-based regimens with glucocorticoids, with selected add-on belimumab or calcineurin inhibitor therapy.