Inflammation of the kidneys caused by an autoimmune disease called systemic lupus erythematosus. The condition can cause hematuria and proteinuria, and it may progress to end-stage renal disease. The most severe form of lupus nephritis, called diffuse proliferative nephritis, can cause scars to form in the kidneys. Scars are permanent, and kidney function often declines as more scars form. Early diagnosis and treatment may help prevent long-lasting damage.