Lupus nephritis
Lupus nephritis is immune complex glomerulonephritis arising from systemic lupus erythematosus, classified by kidney biopsy into ISN/RPS classes I through VI, with class III, IV, or V disease defined by proteinuria above 500 mg per 24 hours. Class-directed immunosuppressive induction pairs pulse glucocorticoids with mycophenolate mofetil or cyclophosphamide, followed by mycophenolate mofetil or azathioprine maintenance, on a background of hydroxychloroquine and renin-angiotensin-system blockade.
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What this article covers
- Overview
Definition: lupus nephritis is immune complex glomerulonephritis from kidney-targeted autoimmunity in systemic lupus erythematosus (SLE); this article covers only the renal manifestation (systemic lupus erythematosus).
- Epidemiology
Prevalence within SLE: up to 50% of patients have clinically evident kidney disease at SLE diagnosis, rising to up to 75% during follow-up; nonwhite women are affected more often, and class IV…
- Risk factors
A diagnosis of SLE itself: the dominant risk factor for developing lupus nephritis.
- Pathophysiology
Immune complex formation: anti-dsDNA antibodies bind nucleosomal antigens to form circulating complexes, and a smaller fraction of autoantibodies bind chromatin directly in the glomerular basement membrane (GBM) and mesangium.
- Clinical features
Early disease is often silent: class I shows no abnormality despite isolated mesangial deposits, and class II produces only microscopic hematuria with low-grade proteinuria.
- Differential diagnosis
IgA nephropathy: also causes hematuria and proteinuria with mesangial deposits, but complement is normal (unlike the low C3 and C4 of active lupus nephritis) and immunofluorescence shows dominant…
- Diagnosis
Kidney biopsy is the definitive step: lupus nephritis is suspected from labs but confirmed only by biopsy, which classifies disease under the International Society of Nephrology/Renal Pathology…
- Management
First, start background therapy in every patient regardless of class: hydroxychloroquine up to 5 mg/kg/day (actual body weight) PO indefinitely, plus losartan 50 to 100 mg PO once daily…
- Complications
Progressive kidney failure: untreated disease can progress to failure requiring dialysis or transplant, and up to 30% progress to ESKD within 10 years despite treatment.
- Prognosis
Response to induction drives long-term outcome: patients reaching remission or partial remission have better renal survival than nonresponders.
- Prevention
Screen every patient with SLE regularly: blood pressure, creatinine, and urinalysis with microscopy at least twice a year, more often if abnormal.
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- Systemic lupus erythematosus
Systemic lupus erythematosus is a chronic multisystem autoimmune disease in which antinuclear and other autoantibodies drive immune-complex deposition and organ injury across skin, joints, kidneys, blood, serosa, and the nervous system. Diagnosis rests on a positive antinuclear antibody plus weighted 2019 EULAR/ACR criteria totaling 10 or more points. Hydroxychloroquine is lifelong first-line therapy for nearly every patient, with glucocorticoids and steroid-sparing immunosuppression added for moderate to severe or organ-threatening disease.
- Membranous nephropathy
Membranous nephropathy is the leading cause of nephrotic syndrome in white adults, most often a primary autoimmune disease driven by anti-PLA2R antibodies against a podocyte antigen, diagnosed by kidney biopsy or noninvasively by anti-PLA2R serology. Patients with persistent nephrotic-range proteinuria after a period of conservative observation are treated with cyclical glucocorticoid-cyclophosphamide, a calcineurin inhibitor, or rituximab.
- IgA nephropathy
IgA nephropathy is the most common primary glomerular disease worldwide, caused by galactose-deficient IgA1 immune complexes depositing in the mesangium, presenting classically with synpharyngitic gross hematuria in young adults and confirmed by kidney biopsy showing dominant mesangial IgA deposits. First-line therapy is renin-angiotensin system blockade, since roughly 40% of patients progress to end-stage kidney disease within 15 years despite treatment.
- Antiphospholipid syndrome
Antiphospholipid syndrome is an acquired autoimmune thrombophilia in which antiphospholipid antibodies cause recurrent venous and arterial thrombosis and pregnancy morbidity, paradoxically prolonging the aPTT in vitro while promoting clotting in vivo. Diagnosis requires a qualifying clinical event plus a laboratory antibody confirmed positive on two occasions at least 12 weeks apart, and thrombotic disease is treated with indefinite warfarin rather than a DOAC.
- Chronic kidney disease
Chronic kidney disease is abnormal kidney structure or function present for more than 3 months, staged by the Kidney Disease: Improving Global Outcomes (KDIGO) system using estimated glomerular filtration rate and albuminuria, and managed with blood pressure control, renin-angiotensin blockade, an SGLT2 inhibitor, and correction of its metabolic complications.