Inflammation of the glomeruli, the tiny filtering units of the kidney

  • Most common in children and young adults
  • More common in males
  • Genetics and lifestyle are not significant factors

Glomerulonephritis is an uncommon disorder in which many of the tiny filtering units of the kidneys, known as glomeruli, become inflamed. As a result, the kidneys are unable to carry out their usual function of removing waste products and excess water from the body efficiently. Blood cells and protein, which normally remain in the blood, leak through the glomeruli into the urine.

Glomerulonephritis can be a short-term (acute) or long-standing (chronic) disorder. An episode with a sudden onset is usually followed by complete recovery, but in severe cases damage to the glomeruli may be permanent. Chronic glomerulonephritis sometimes develops after an acute attack. Progressive kidney damage then occurs over several months or years as a result of continuing inflammation. Most people who develop glomerulonephritis have no previous history of kidney disease.

Although glomerulonephritis affects both kidneys, not all of the glomeruli may be affected to the same degree.

What are the causes?

Acute glomerulonephritis sometimes occurs as a complication of certain infectious diseases. The antibodies that are produced by the immune system to fight the infection attack the glomeruli in the kidneys, causing inflammation and damage. The most common cause of acute glomerulonephritis, especially in children, is a bacterial throat infection, such as a streptococcal infection. Occasionally, acute glomerulonephritis develops after a viral infection, such as infectious mononucleosis. In developing countries, the disorder may occur as a result of parasitic diseases, such as malaria.

Chronic glomerulonephritis is usually caused by a response of the immune system in which certain antibodies of the immunoglobulin A type are deposited in the kidney tissues. Chronic glomerulonephritis may also be associated with autoimmune disorders that affect many organs in the body, such as systemic lupus erythematosus.

What are the symptoms?

In acute glomerulonephritis, symptoms develop rapidly over a few days. In contrast, the initial symptoms of chronic glomerulonephritis develop slowly and may only become apparent when the kidneys have already been severely damaged. The symptoms of both forms of the disorder may include:

  • Frequent passing of urine.

  • Frothy or cloudy urine.

  • Blood in the urine.

  • Puffiness of the face, with swelling around the eyes in the morning.

  • Swollen feet and legs in the evening.

  • Shortness of breath.

  • Loss of appetite.

A serious complication of glomerulonephritis is high blood pressure (see Hypertension), which may result in further damage to the kidneys.

How is it diagnosed?

In the initial stages of chronic glomerulonephritis there may be no symptoms, and the condition may only be diagnosed during routine screening tests or investigations for another disorder. If you do develop symptoms of acute or chronic glomerulonephritis, the doctor may test a urine sample to detect blood and protein. Further urine tests and a blood test may be necessary to assess kidney function. In addition, your doctor may arrange for imaging tests to assess the size of your kidneys because the kidneys are likely to become larger in cases of acute glomerulonephritis and to shrink in chronic glomerulonephritis. The imaging tests usually include X-rays or ultrasound scanning, and intravenous urography, a form of X-ray in which the urinary tract is highlighted with a contrast dye. However, the use of this dye is avoided in people with suspected serious kidney problems. A kidney biopsy may also be needed to determine the cause of the kidney damage.

What is the treatment?

Treatment depends on the severity and, if known, the cause of the disorder. Some cases are so mild that they do not need treatment and are simply monitored. If the disorder follows a bacterial infection, antibiotics and sometimes corticosteroids may be prescribed. Glomerulonephritis due to an autoimmune disorder can usually be treated with immunosuppressants and corticosteroids. If the condition is accompanied by high blood pressure, this will be treated with antihypertensive drugs as good control of blood pressure is crucial to preserving kidney function.

What is the prognosis?

In most cases, the symptoms of acute glomerulonephritis disappear after 6–8 weeks. However, the outlook is variable. In some people, kidney function is reduced but does not deteriorate further. Others may develop chronic kidney failure, which can lead to end-stage kidney failure, an irreversible loss of kidney function that may be fatal if not recognized and treated promptly.

From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.

The subjects, conditions and treatments covered in this encyclopaedia are for information only and may not be covered by your insurance product should you make a claim.

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