Glomerulonephritis, a disease of the kidney, is characterized by inflammation of the glomeruli, very small blood vessels in the kidney that serve as tiny filters. The disease damages the kidneys' ability to remove waste and excess fluids from the body. Glomerulonephritis can be acute (a sudden attack of inflammation) or chronic (long-term and comes on gradually). If the illness continues, the kidneys may stop working completely, resulting in kidney failure. Treatment depends on the type of glomerulonephritis you have.
For more information see Glomerulonephritis - National Kidney Foundation.