Lupus nephritis

A kidney disorder associated with systemic lupus erythematosus

Lupus nephritis is an inflammation of the kidneys caused by systemic lupus erythematosus (SLE), an autoimmune disease in which the body's immune system attacks its own tissues. This condition is a serious complication of SLE and can lead to significant kidney damage.

Pathophysiology

Lupus nephritis occurs when autoantibodies form immune complexes that deposit in the glomeruli, the filtering units of the kidneys. This deposition leads to inflammation and damage to the kidney tissues. The exact mechanism involves a complex interplay of genetic, environmental, and immunological factors that result in the production of antinuclear antibodies and other autoantibodies.

Classification

Lupus nephritis is classified into six classes based on the International Society of Nephrology/Renal Pathology Society (ISN/RPS) classification system:

• Class I: Minimal mesangial lupus nephritis - Normal appearance under light microscopy, but immune deposits are present under electron microscopy.
• Class II: Mesangial proliferative lupus nephritis - Mesangial hypercellularity and immune deposits.
• Class III: Focal lupus nephritis - Involves less than 50% of all glomeruli.
• Class IV: Diffuse lupus nephritis - Involves more than 50% of glomeruli and is the most severe form.
• Class V: Membranous lupus nephritis - Characterized by thickening of the glomerular basement membrane.
• Class VI: Advanced sclerosing lupus nephritis - Represents end-stage renal disease with more than 90% of glomeruli sclerosed.

Symptoms

Symptoms of lupus nephritis can vary widely but often include:

• Hematuria (blood in the urine)
• Proteinuria (excess protein in the urine)
• Hypertension (high blood pressure)
• Edema (swelling, particularly in the legs, ankles, and feet)
• Renal insufficiency

Diagnosis

Diagnosis of lupus nephritis typically involves a combination of laboratory tests and a kidney biopsy. Laboratory tests may include:

• Urinalysis to detect proteinuria and hematuria
• Blood tests to assess kidney function, such as serum creatinine and glomerular filtration rate (GFR)
• Antinuclear antibody test (ANA) and other specific autoantibody tests

A kidney biopsy is often performed to determine the class of lupus nephritis and guide treatment decisions.

Treatment

Treatment of lupus nephritis aims to reduce inflammation, prevent kidney damage, and preserve kidney function. Common treatments include:

• Corticosteroids to reduce inflammation
• Immunosuppressive drugs such as cyclophosphamide, mycophenolate mofetil, and azathioprine
• Biologic agents like rituximab or belimumab
• Antihypertensive medications to control blood pressure
• Angiotensin-converting enzyme inhibitors (ACE inhibitors) or angiotensin receptor blockers (ARBs) to reduce proteinuria

Prognosis

The prognosis of lupus nephritis varies depending on the class and severity of the disease, as well as the response to treatment. Early diagnosis and aggressive treatment can improve outcomes and reduce the risk of progression to end-stage renal disease.

Related pages

• Systemic lupus erythematosus
• Autoimmune disease
• Kidney disease
• Glomerulonephritis