Lupus and the Kidney: The Six Classes of Lupus Nephritis, the 2024 Treatment Shift (belimumab, voclosporin, obinutuzumab), and When Dialysis or Transplant Comes In
About 40–60% of people with systemic lupus erythematosus develop lupus nephritis, a leading cause of kidney failure in young women. Why a biopsy is essential, what the six classes mean, the move to low-dose steroids and triple therapy, and what is different for lupus patients on dialysis or waiting for a transplant.
Who this is for: people newly diagnosed with SLE who want to understand kidney risk, patients and families just told they have "lupus nephritis", and those on dialysis or awaiting transplant because of it. Based on the KDIGO 2024 Lupus Nephritis guideline, EULAR 2023 recommendations and the ACR 2024 guideline. It does not replace your own doctor's advice.
1. Why lupus attacks the kidney
Systemic lupus erythematosus (SLE) is an autoimmune disease: the immune system makes antibodies against the body's own nuclear material (anti-dsDNA, anti-Sm and others). Antibody–antigen immune complexes deposit in the glomeruli, triggering inflammation, consuming complement (low C3/C4), and damaging the filter — causing blood and protein in the urine and, when severe, rapid loss of kidney function.
- 40–60% of people with SLE develop kidney involvement; Asians (Taiwanese, Japanese, Korean, Chinese) are affected more often and more severely than white Europeans.
- Most cases appear within 5 years of SLE diagnosis, but nephritis can be the very first sign.
- Untreated or poorly responsive, about 10–30% progress to kidney failure within 10–15 years.
- Peak onset is in women aged 15–45 (female:male ≈ 9:1), making it a major cause of dialysis in young adults.
2. When to suspect lupus nephritis
Everyone with SLE should have urine and kidney function checked every 3–6 months. Any of the following warrants further work-up:
| Red flag | Meaning |
|---|---|
| Urine protein-to-creatinine ratio (UPCR) >0.5 g/g (or 24-h protein >500 mg) | Inflamed glomeruli leaking protein |
| Microscopic haematuria, red-cell casts | Glomerular inflammation |
| Rising creatinine / falling eGFR | Loss of function |
| Leg swelling, foamy urine, rising blood pressure | Nephrotic syndrome or progression |
| Rising anti-dsDNA with falling C3/C4 | Increasing disease activity, higher kidney risk |
3. Why a kidney biopsy is essential
The histological class dictates how aggressive treatment must be — the same amount of proteinuria is managed completely differently in class II versus class IV. Guidelines recommend biopsy whenever UPCR exceeds 0.5 g/g or kidney function falls without another explanation.
The ISN/RPS classes (2003, revised 2018)
| Class | Name | Features | Approach |
|---|---|---|---|
| I | Minimal mesangial | Normal by light microscopy, deposits on immunofluorescence only | No kidney-directed immunosuppression; treat SLE |
| II | Mesangial proliferative | Mesangial hypercellularity | Usually no intensive immunosuppression; consider if proteinuria >1 g |
| III | Focal proliferative | <50% of glomeruli inflamed/necrotic | Induction immunosuppression required |
| IV | Diffuse proliferative | ≥50% of glomeruli involved — the commonest and most severe | Induction immunosuppression required |
| V | Membranous | Thickened basement membrane, nephrotic syndrome | Immunosuppression if proteinuria >3 g or combined with III/IV |
| VI | Advanced sclerosing | ≥90% of glomeruli scarred | Immunosuppression no longer helps; prepare for kidney replacement |
The report also gives an activity index (AI, 0–24) and chronicity index (CI, 0–12): high activity means ongoing inflammation worth treating aggressively; high chronicity means established scarring with little to recover. About 20–30% have mixed classes (III+V, IV+V).
4. Treatment: from "high-dose steroids" to "low-dose steroids plus triple therapy"
Foundation therapy for everyone
- Hydroxychloroquine: lifelong for all SLE patients unless contraindicated; reduces nephritis flares, thrombosis and mortality. Dose ≤5 mg/kg/day; annual retinal screening after 5 years of use.
- ACE inhibitor or ARB for any proteinuria.
- Blood pressure <130/80, statin for lipids, sun protection, stop smoking, and a contraception plan (most drugs below are teratogenic).
Induction for class III/IV (±V) — the first 6 months
KDIGO 2024 standard: glucocorticoids (far lower doses than before) plus one of these:
| Regimen | Details | Notes |
|---|---|---|
| MMF (mycophenolate) | 2–3 g/day | As effective as low-dose cyclophosphamide, spares fertility, works well in Asians; the most common first choice |
| Low-dose IV cyclophosphamide (Euro-Lupus) | 500 mg every 2 weeks × 6 | Preferred with rapidly falling GFR or many crescents; low cumulative dose, little ovarian toxicity |
| MMF + belimumab | 10 mg/kg IV monthly or 200 mg SC weekly | BLISS-LN (2020): higher complete renal response at 2 years, fewer flares; KDIGO 2024 lists it as an initial triple-therapy option |
| MMF + calcineurin inhibitor (voclosporin or tacrolimus) | voclosporin 23.7 mg twice daily | AURORA 1 (2021): complete renal response 41% vs 23% at 1 year; best for heavy proteinuria with eGFR >45; low-dose tacrolimus "multitarget" therapy is widely used in Asia |
| Obinutuzumab (anti-CD20) + MMF | 1,000 mg IV at weeks 0, 2, 24, 26 | REGENCY (NEJM Feb 2025): complete renal response 46% vs 33% at 76 weeks; FDA-approved for lupus nephritis October 2025 |
The new consensus on steroids
- After IV methylprednisolone pulses (250–500 mg × 3 days), oral prednisolone starts at ≤0.5 mg/kg/day (previously 1 mg/kg) and is tapered to ≤5 mg/day within 6 months, stopping if possible.
- Why: osteoporosis, avascular necrosis, diabetes, cataracts, infection and cardiovascular disease from long-term steroids are one of the largest sources of organ damage in lupus.
Maintenance (at least 3 years)
- MMF 1–2 g/day or azathioprine 1.5–2 mg/kg/day (azathioprine if pregnancy is planned).
- Belimumab or voclosporin used in induction may be continued.
- After ≥3 years (some say ≥5) of complete remission, gradual withdrawal can be discussed — but hydroxychloroquine continues.
Judging response
- Complete renal response: UPCR <0.5 g/g and eGFR back to normal or within 10–15% of baseline.
- Proteinuria should fall ≥25% by 3 months, ≥50% by 6 months, and UPCR should be <0.5–0.7 by 12 months; if not, switch therapy or re-biopsy.
5. Flares, pregnancy and daily life
- 30–50% flare after stopping treatment; each flare adds scarring. Regular urine testing is the cheapest, most effective monitoring.
- Pregnancy: aim for stable disease ≥6 months (UPCR <0.5, no active nephritis) before conceiving. MMF, cyclophosphamide and ACEi/ARB are teratogenic and must be switched beforehand (azathioprine, tacrolimus and hydroxychloroquine are pregnancy-compatible). Shared care between rheumatology, nephrology and high-risk obstetrics.
- Infection prevention: Pneumocystis prophylaxis (TMP-SMX) during cyclophosphamide or high-dose steroids; antiviral cover for hepatitis B carriers; influenza, pneumococcal and (non-live) shingles vaccines; avoid live vaccines.
- Bones: calcium, vitamin D and bisphosphonates if needed while on long-term steroids.
- Heart: myocardial infarction risk is 5–10 times that of peers — control blood pressure and lipids, stop smoking.
6. Reaching dialysis
- 10–30% eventually reach kidney failure, usually class IV, delayed treatment, repeated flares, or antiphospholipid syndrome with renal vascular disease.
- SLE activity often quietens after starting dialysis (uraemia itself is immunosuppressive); most can reduce or stop immunosuppressants, but hydroxychloroquine should continue and joints, skin, blood counts and neurological symptoms still need follow-up.
- Both haemodialysis and peritoneal dialysis work; with antiphospholipid antibodies, vascular access clots more easily and fistulas need extra care.
- Keep seeing rheumatology after dialysis starts — "the kidneys failed, so lupus is over" is a dangerous assumption.
7. Kidney transplant
- Graft survival in lupus nephritis is comparable to other causes — transplant is an excellent option.
- Aim for clinical and serological quiescence for 6–12 months first; antiphospholipid antibodies raise post-transplant thrombosis risk and need an anticoagulation plan.
- Recurrence in the graft is uncommon (about 2–11%) and usually mild, because transplant immunosuppression (tacrolimus, MMF) also treats lupus.
- Continue hydroxychloroquine after transplant; studies suggest fewer rejections and cardiovascular events.
- First-degree living donors should be screened to confirm they do not have SLE or another autoimmune disease (lupus clusters in families).
8. Common questions
Q: Is a biopsy dangerous? A: Serious bleeding needing transfusion occurs in about 1–2% of ultrasound-guided biopsies; surgery is needed in <0.1%. Antiplatelets/anticoagulants are stopped and blood pressure and clotting checked beforehand. The information gained far outweighs the risk.
Q: Can biologics replace steroids altogether? A: Not yet — but belimumab, voclosporin and obinutuzumab allow much lower steroid doses, which is itself the biggest win.
Q: Is class V "mild"? A: Pure class V progresses slowly, but years of heavy proteinuria cause clots, high lipids and gradual loss of function, so it still needs treatment; combined with III/IV it is managed as proliferative disease.
Q: Herbal medicines and supplements? A: Many herbal products (especially those containing aristolochic acid) are nephrotoxic; "immune-boosting" supplements (echinacea, spirulina, alfalfa) may theoretically stimulate lupus activity. Discuss anything new with your doctor first.
Sources
- KDIGO. 2024 Clinical Practice Guideline for the Management of Lupus Nephritis. Kidney Int 2024;105(1S):S1–S69. https://kdigo.org/guidelines/lupus-nephritis/
- Fanouriakis A, et al. EULAR recommendations for the management of SLE: 2023 update. Ann Rheum Dis 2024;83:15–29.
- American College of Rheumatology. 2024 Guideline for the Screening, Treatment, and Management of Lupus Nephritis. https://rheumatology.org/lupus-nephritis-guideline
- Furie R, et al. BLISS-LN. N Engl J Med 2020;383:1117–1128.
- Rovin BH, et al. AURORA 1. Lancet 2021;397:2070–2080.
- Furie RA, et al. REGENCY. N Engl J Med 2025;392:1471–1483.
- Bajema IM, et al. Revision of the ISN/RPS classification for lupus nephritis. Kidney Int 2018;93:789–796.
- Anders HJ, et al. Lupus nephritis. Nat Rev Dis Primers 2020;6:7.
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