Rapidly progressive glomerulonephritis includes any type of glomerulonephritis (inflammation of the glomerulus) in which progressive loss of kidney function occurs over days to weeks rather than months to years, and in which a kidney biopsy shows crescents in at least 75% of the glomeruli. It may manifest itself as an acute nephritic syndrome or unexplained renal failure. It progresses rapidly to renal failure and end-stage renal disease.
The disorder occurs in about 1 out of 10,000 people. It is most common in people 40 to 60 years old, and slightly more common in men but, depending on the cause, occurs in both sexes and at any age. It is unusual in preschool children, and slightly more common in later childhood.