Glomerulonephritis 

Glomerulonephritis is a condition that affects the kidneys.

It happens when tiny structures inside the kidney, called glomeruli, become diseased. This can be caused by several conditions, but it is often caused by the immune system (the body's natural deference against infection and illness).

Glomerulonephritis may not cause any symptoms and is often diagnosed when blood or urine tests are carried out for another reason. See Glomerulonephritis - symptoms for more information. 

Glomerulonephritis can vary in severity. It can be short-lived (acute) or it can last for a long time (chronic).

Several medicines can be used to treat glomerulonephritis, depending on its cause and how severe it is. See Glomerulonephritis - treatment for more information.

Glomeruli

You have two kidneys in your body. They have a very important function in removing waste products from your blood. These are then passed out of your body in urine.

In each kidney are about 1 million tiny filters called glomeruli. Glomeruli filter waste products from the blood into the urine, while keeping the necessary cells and proteins in the blood. Glomerulonephritis occurs when the glomeruli become affected by one of a wide range of possible diseases.

If the kidneys become affected in this way, they cannot work properly, which causes kidney disease. This can lead to:

• protein from your blood leaking into your urine
• red blood cells being detected in your urine
• waste products and fluid building up in your body

This can cause complications, such as high blood pressure (hypertension). If the kidneys are severely affected, they may no longer work. This is known as kidney failure.

Types of glomerulonephritis

There are several types of glomerulonephritis. However, the condition can be broadly split into two main types: 

• Primary glomerulonephritis develops on its own and is not related to another condition.
• Secondary glomerulonephritis develops as a result of another condition.

Conditions that can cause secondary glomerulonephritis include:

• systemic lupus erythematosus
• vasculitis

These are autoimmune conditions. An autoimmune condition is where your immune system reacts abnormally. Instead of doing its usual job of fighting infection, it attacks your body's healthy tissues.

In most cases, the cause of primary glomerulonephritis is unknown. However, in some cases, a specific cause can be found, such as a reaction to a viral infection or medication. See Glomerulonephritis - causes for more information.