Excerpt from Nephritis, Lupus

Synonyms, Key Words, and Related Terms: lupus nephritis, systemic lupus erythematosus, SLE, end-stage renal disease, ESRD, end-stage kidney disease, chronic kidney disease, chronic renal disease, chronic renal failure, glomerulonephritis, hematuria, renal failure, kidney failure, mesangial nephritis, hypertension, proteinuria, active lupus nephritis, focal proliferative lupus nephritis, diffuse proliferative lupus nephritis, mesangial lupus nephritis, membranous lupus nephritis, active nephritis, sclerosing lupus nephritis, mesangial proliferative lupus nephritis, focal lupus nephritis, diffuse lupus nephritis, focal sclerosing lupus nephritis, diffuse segmental proliferative lupus nephritis, diffuse global proliferative lupus nephritis, diffuse segmental sclerosing lupus nephritis, diffuse global sclerosing lupus nephritis, advanced sclerosis lupus nephritis

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Background: Lupus nephritis, one of the most serious manifestations of systemic lupus erythematosus (SLE), usually arises within 5 years of diagnosis; however, renal failure rarely occurs before American College of Rheumatology classification criteria are met.

Histological evidence of lupus nephritis is present in most patients with SLE, even if they do not have clinical manifestations of renal disease. The symptoms are generally related to hypertension, proteinuria, and renal failure. With the advent of more aggressive immunosuppressive and supportive therapy, rates of renal involvement and patient survival are improving.

Pathophysiology: Autoimmunity plays a major role in the pathogenesis of lupus nephritis. The immunologic mechanisms include production of autoantibodies directed against nuclear elements. These autoantibodies form pathogenic immune complexes. In the kidneys, deposition of these immune deposits initiates an inflammatory response by activating the complement cascade and recruiting inflammatory cells that can subsequently be observed on biopsy specimens.

Frequency:

In the US: The prevalence of SLE is 1 case per 2000 in the general population. Because of the difficulty in diagnosis and a probable underestimation of SLE cases, researchers suggest that the prevalence may be closer to 1 case per 500-1000 population.
Histologically, the kidneys are affected to some degree in most patients with SLE. Estimates of the prevalence of clinical renal involvement in persons with SLE range from 30-90% in published studies. The true prevalence of clinical lupus nephritis is probably around 50%, being more common in certain ethnic groups and in children.

Mortality/Morbidity:

Over the last 4 decades, changes in the treatment of lupus nephritis and general medical care have greatly improved both renal involvement and overall survival. During the 1950s, the 5-year survival rate among patients with lupus nephritis was close to 0%. Recently, with the addition of immunosuppressive agents such as intravenous pulse cyclophosphamide, the 5- and 10-year survival rates are documented as high as 85% and 73%, respectively.

Morbidity is related to the renal disease itself, as well as to treatment-related complications and comorbidities, including cardiovascular disease and thrombotic events. Progressive renal failure leads to anemia, uremia, and electrolyte and acid-based abnormalities. Hypertension may lead to an increased risk of coronary artery disease and stroke. Nephrotic syndrome may lead to edema, ascites, and hyperlipidemia, which add to the risk of coronary artery disease and the potential for thrombosis.

Therapy with corticosteroids, cyclophosphamide, and other immunosuppressive agents leads to increased risk of infection. Long-term corticosteroid therapy may lead to osteoporosis, avascular necrosis, diabetes mellitus, and hypertension, among other complications. Cyclophosphamide therapy may cause cytopenias, hemorrhagic cystitis, infertility, and an increased risk of malignancy.

Race: SLE is more common in black people and Hispanic people than in white people. Black people and Asian people may have a higher prevalence of more severe lupus nephritis than other ethnic groups.

Sex: Lupus nephritis is more common in females because the overall prevalence of SLE is higher in females (ie, female-to-male ratio of 9:1); however, males with SLE have an increased prevalence of clinical renal disease with a worse prognosis.

Age: Most patients develop lupus nephritis early in their disease course. SLE is more common among women in the third decade of life, and lupus nephritis occurs in patients aged 20-40 years.