- Renal disease associated with systemic lupus erythematosus (SLE)
- A kidney biopsy is necessary to confirm the diagnosis (1).
- Clinical manifestations primarily due to immune complex–mediated glomerular disease; tubulointerstitial and vascular involvement often coexist. Diagnosis is based on clinical findings, urine abnormalities, autoantibodies, and renal biopsy.
- Treatment and prognosis depend on severity of disease.
- Early diagnosis improves renal outcomes.
- Peak incidence of SLE is 15 to 45 years of age. Mean age of diagnosis is between 25 and 30 years of age.
- The lifetime incidence of lupus nephritis (LN) in patients with SLE is 20–60%.
- Predominant sex: female > male (10:1)
- Once SLE develops, LN affects both genders equally; it is more severe in children and men and less severe in older adults.
- More common in African American and Asian populations
- SLE: 1 to 22/100,000 people
- Up to 60% of SLE patients develop LN over time; 25–50% of SLE patients have nephritis as the initial presentation.
LN is more common and more severe in children: 60–80% of children have LN at or soon after SLE onset.
SLE: 7 to 159/100,000 people
Etiology and Pathophysiology
- Immune complex–mediated inflammation injures glomeruli, tubules, interstitium, and vasculature.
- Glomeruli: Varying degrees of mesangial proliferation, crescent formation, and fibrinoid necrosis cause reduced glomerular filtration rate (GFR).
- Persistent inflammation (chronicity) leads to sclerosis and glomerular loss.
- Tubulointerstitial injury (edema, inflammatory cell infiltrate acutely; tubular atrophy in chronic phase) with or without tubular basement membrane immune complex deposition leads to reduced renal function.
- Vascular lesions: immune complex deposition and noninflammatory necrosis in arterioles
- SLE is a multifactorial disease, with multigenic inheritance; exact etiology remains unclear.
- Defective T-cell autoregulation and polyclonal B-cell hyperactivity contribute to dysregulated apoptosis. Impaired clearance of apoptotic cells inhibits self-tolerance to nuclear antigen.
- Anti-DNA, anti-C1q, anti–α-actin, and other nuclear component autoantibodies develop.
- Deposition of circulating immune complexes or autoantibodies attaching to local nuclear antigens leads to complement activation, inflammation, and tissue injury.
- Interaction of genetic, hormonal, and environmental factors leads to great variability in LN severity.
- Polygenic inheritance; clustering in families, ~25% concordance in identical twins
- Interaction of general SLE susceptibility genes with more renal-specific genes and epigenetic changes
Younger age, African American or Hispanic race, more ACR criteria for SLE, longer disease duration, hypertension, lower socioeconomic status, family history of SLE, anti-dsDNA antibodies, low albumin to globulin ratio
Commonly Associated Conditions
Other organ systems often involved in SLE.
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