Definition of Lupus nephritis:

Lupus nephritis is a kidney disorder that is a complication of systemic lupus erythematosus.

Causes, incidence, and risk factors:

Lupus nephritis occurs when antibodies (antinuclear antibody and others) and complement build up in the kidneys, causing inflammation. It often causes nephrotic syndrome (excessive protein excretion) and may progress rapidly to renal failure. Nitrogen waste products build up in the bloodstream.

Systemic lupus erythematosus (SLE) causes various disorders of the internal structures of the kidney, including interstitial nephritis and membranous GN. Lupus nephritis affects approximately 3 out of 10,000 people. In children with SLE, about half will have some form or degree of kidney involvement.

SLE is most common in women 20-40 years old. For more information, see the general article on systemic lupus erythematosus.