Glomerulonephritis

What Is It?

Glomerulonephritis is inflammation of the filtering units of the kidneys, which are called glomeruli. This inflammation can cause too much protein and other substances to leak from the blood into the urine. Eventually, the kidney becomes less effective at filtering out waste products, water and salt from the blood, a condition called kidney failure. When this occurs, waste products build up to very high levels in the blood, and the body retains salt and water. When very large amounts of protein are lost in the urine, the person also can retain fluid and develop high cholesterol.

Glomerulonephritis can be a complication of streptococcal infections, including strep throat, particularly in children ages 6 to 10. Less often, it results from other bacterial or viral infections, especially measles, mumps, mononucleosis and HIV. Other causes include some problems with the immune system (especially those involving immunoglobulin A antibodies), systemic lupus erythematosus (also called SLE or lupus), and inflammation of the kidney's blood vessels (vasculitis). Sometimes, the cause can't be identified.

Doctors divide glomerulonephritis into different types, depending on the cause of the illness, its symptoms and the kind of urine problems it causes. Three examples of these types are:

• Acute postinfectious glomerulonephritis — This form of glomerulonephritis follows an infection and often causes high blood pressure, dark urine, water retention and swelling because of kidney failure.
• Mesangial glomerulonephritis — This type seems to be related to immune-system abnormalities involving a type of antibody called immunoglobulin A (IgA). In most cases, the cause of this immune problem is not known, though it may be associated with a number of conditions, including cirrhosis of the liver, celiac disease (also called gluten enteropathy, celiac sprue or non-tropical sprue) and HIV infection. It can cause red blood cells to spill into the urine, but rarely causes high blood pressure, leg swelling or kidney failure.
• Membranous glomerulonephritis —In this disease, the glomeruli leak large amounts of protein into the urine from the blood.

Symptoms

If glomerulonephritis is mild, it will not cause any symptoms. When that happens, the disease is discovered only if protein or blood is found in the urine during a routine test. In other people, the first clue can be the development of high blood pressure. If symptoms appear, they can include swelling around the eyes, reduced urination and dark urine from the presence of red blood cells in the urine. If high blood pressure develops, some people will have headaches. If a large amount of protein is lost in the urine, there also can be swelling, particularly of the face, abdomen, lower legs, ankles or feet.