Lupus Nephritis

Overview – Lupus Nephritis

Lupus nephritis is an immune-mediated inflammation of the kidneys caused by systemic lupus erythematosus (SLE). It affects up to 60% of patients with SLE and represents a major cause of morbidity and mortality in this autoimmune condition. Lupus nephritis results from immune complex deposition in the glomeruli, leading to glomerular damage, proteinuria, nephrotic syndrome, and eventual renal impairment. Early recognition and immunosuppressive therapy are key to preserving renal function.

Definition

• Lupus nephritis is kidney inflammation secondary to systemic lupus erythematosus (SLE), an autoimmune condition.
• Characterised by immune complex-mediated glomerulonephritis.

Aetiology

• Autoimmune complication of SLE
• More common in women and in patients of non-Caucasian ethnic backgrounds
• Triggered by immune dysregulation and circulating autoantibodies

Pathophysiology

• Immune complexes (DNA-anti-DNA) deposit in glomerular basement membrane →
  • Triggers complement activation and inflammatory cascade
  • Glomerular basement membrane (GBM) damage
  • → Nephrotic-range proteinuria
  • → Tubulointerstitial involvement in severe cases

Clinical Features

• Present in up to 60% of SLE patients
• Oedema (legs, ankles, feet, face, and hands)
• Weight gain (due to fluid retention)
• Hypertension
• Dark or frothy urine
• Nephrotic syndrome features:
  • ++ Proteinuria (often selective)
  • Oedema
  • Polyuria

Investigations

• Autoimmune markers:
  • ANA titre
  • Anti-dsDNA
  • Anti-Smith antibodies
• Urinalysis:
  • Proteinuria, haematuria, cellular casts
• Renal ultrasound – to assess structure and exclude obstruction
• Definitive diagnosis:
  • Kidney biopsy (important for histological classification and guiding therapy)

Management

• Corticosteroids – mainstay for acute inflammation
• NSAIDs – for symptomatic relief
• Immunosuppressive therapy:
  • Methotrexate
  • Sulfasalazine
  • Cyclophosphamide (used in severe cases or Class III–IV LN)
• Renal support therapy:
  • Dialysis (if renal failure progresses)
  • Transplant in end-stage renal disease

Complications

• Progression to chronic kidney disease or ESRF
• Increased risk of cardiovascular events
• Opportunistic infections (from immunosuppression)
• Recurrent lupus flares affecting other organs

Differential Diagnosis

• IgA nephropathy
• Post-infectious glomerulonephritis
• Membranous nephropathy
• Focal segmental glomerulosclerosis
• Diabetic nephropathy

Summary – Lupus Nephritis

Lupus nephritis is a serious renal manifestation of systemic lupus erythematosus, caused by immune complex deposition and glomerular inflammation. It can lead to nephrotic syndrome, fluid retention, and progressive renal dysfunction. Early detection, immunosuppressive therapy, and close monitoring are vital to preserve renal function. For a broader context, see our Renal Overview page.