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Class IV Lupus Nephritis — RACP Adult Medicine MCQ

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ModerateNephrologyClass IV Lupus NephritisRACP Adult Medicine

A 45-year-old woman with SLE presents with nephrotic-range proteinuria (5 g/day), haematuria (dysmorphic RBCs, RBC casts), and rising creatinine. Anti-dsDNA is strongly positive. C3 and C4 are both very low. Renal biopsy shows diffuse endocapillary and extracapillary proliferation (crescents in 40% of glomeruli) with full-house immunofluorescence (IgG, IgA, IgM, C3, C1q). What WHO/ISN class is this?

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Correct answer: A — Lupus nephritis

Mixed nephrotic-nephritic picture in SLE with low C3 AND C4 (classical pathway activation), positive anti-dsDNA, and biopsy showing diffuse proliferative GN with full-house IF and 40% crescents is Class IV lupus nephritis (the most common and severe class). Treatment per EULAR/KDIGO: induction with MMF + low-dose prednisolone (or cyclophosphamide for severe disease), consider adding voclosporin or belimumab. Maintenance with MMF + HCQ long-term.

Reference: KDIGO – 2021 – GN; EULAR 2024 Lupus Nephritis