Glomerulonephritis is a disease of the kidneys in which there is inflammation of the filtering units, called glomeruli. This inflammation can cause protein and red blood cells to leak into the urine while toxins normally removed by the kidney are retained in the body. Kidney failure develops when the kidney becomes less effective at filtering out waste products, water and salt from the blood.
There are many types and causes of glomerulonephritis. These include:
Prior infection: For example, after a streptococcal infection (such as strep throat), kidney failure may develop with associated problems of high blood pressure, dark urine, and swelling in the legs. Glomerulonephritis following streptococcal bacterial infection is among the most common types of post-infectious disease, especially among children.
Autoimmune: With conditions such as systemic lupus erythematosus (SLE) or blood vessel inflammation (vasculitis), the body's immune system mistakenly attacks healthy tissue. When the kidney's filtering system is the target, glomerulonephritis may develop.
Antibody-mediated: The most common type is called IgA nephropathy. While this can be associated with liver disease, celiac disease or HIV infection, many cases are of unknown cause. Immunoglobulin A, an antibody that normally helps fight off infection, is deposited in the kidney, leading to hematuria (blood in the urine) but less commonly more serious problems.
Membranous glomerulonephritis: This condition may develop as part of lupus or on its own. The hallmark of this type of kidney disease is the leakage of protein into the urine.
Rapidly progressive glomerulonephritis: This condition may be diagnosed when there is kidney inflammation and loss of kidney function over weeks to months. Triggers include infections, autoimmune disease, and certain types of antibody-mediated kidney disease.
Idiopathic: When glomerulonephritis develops for no apparent reason it is called "idiopathic." It's possible that an undetected or undiagnosed infection or a hereditary cause led to kidney inflammation and damage.