Introduction

Glomerulonephritis is the name for a family of diseases which affect the kidneys. Glomerulo refers to the glomeruli, or the tiny filters in the kidney, and nephritis means inflammation in the kidney.
Damage to the glomeruli is caused by the body's immune (natural defence) system. The usual job of the immune system is to fight invaders into the body. 

These might be germs or bugs, or foreign objects such as splinters. The body recognises these invaders and tries to eliminate them from the body. It is not clear why the immune system causes diseases such as glomerulonephritis. There may be some trigger that makes the immune system go wrong, such as an infection. Often it is not known why glomerulonephritis occurs.

Most people with glomerulonephritis have minor disease, and it may only cause tiny amounts of blood and protein to appear in the urine, without any other symptoms. However, occasionally there can be high blood pressure and kidney failure.

Symptoms

Often there are no symptoms at all, and someone is diagnosed as having glomerulonephritis only because the urine has been checked at a routine medical check-up, or because someone has high blood pressure, or is pregnant, and urine tests are routinely carried out.
Because there are many types of glomerulonephritis, there are many symptoms that can occur.

Glomerulonephritis can cause water retention in the body, with swollen ankles or a puffy face. Small amounts of blood in the urine may be invisible to the naked eye, but sometimes the urine turns red with blood. If glomerulonephritis causes high blood pressure there may be headaches. Some types of glomerulonephritis are associated with a blotchy red skin rash; these require urgent diagnosis and treatment by a specialist.

Glomerulonephritis is usually painless, but some people do get pain in the kidneys (in the upper back, behind the ribs). This can be hard to distinguish from pain arising from the muscles of the back. Also, kidney pain is much more often due to infection than to glomerulonephritis. Sometimes the pain is severe and is called ‘loin pain haematuria syndrome’

Causes

Glomerulonephritis is a term most commonly used by doctors for a family of diseases where damage to the glomeruli is caused by the body's immune (natural defence) system. The usual job of the immune system is to fight invaders into the body.

These might be germs or bugs, or foreign objects such as splinters. The body recognises these invaders and tries to eliminate them from the body. The blood contains two main types of defence system. One is white blood cells, which stick to germs and kill them.

The other type of defence is antibodies, which are smaller than the white blood cells and, by sticking onto germs, either make them burst apart or help the white blood cells to stick to them.
The immune system is very powerful and is normally very good at recognising what is part of the body and what is not.

However, sometimes it makes a mistake and attacks the body as if it was an invader. There are many different diseases caused by the immune system, and they can affect any part of the body. There are several kidney diseases caused by the immune system. Some of them affect only the kidneys, some can affect other parts of the body as well as the kidneys.

It is not clear why the immune system causes diseases such as glomerulonephritis. There may be some trigger that makes the immune system go wrong, such as an infection, but usually this cannot be identified.

Diagnosis

Doctors consider glomerulonephritis in anyone with kidney disease, but problems such as infection are much commoner. If glomerulonephritis is suspected, some blood tests will be performed to look for abnormal antibodies in the blood.
However, it is not possible to make an accurate diagnosis in most cases by blood tests alone.

To be sure of making a diagnosis, a kidney biopsy must be performed. A biopsy is the removal of a fragment of kidney to examine under the microscope. This test carries a small risk of bleeding, and not everyone with possible glomerulonephritis requires a biopsy.

Treatment

Although glomerulonephritis is usually caused by over-activity of the immune system, drugs that suppress the immune system do not cure or improve glomerulonephritis in most cases. This is because the drugs suppress the immune system generally, and lead to a high risk of complications if used in high doses.

In most people with glomerulonephritis, treatment is based on controlling the blood pressure. High blood pressure damages the kidney further, and also the circulation elsewhere in the body. Blood pressure can be controlled by losing excess weight, reducing salt intake in the diet, and by the use of drugs.

Drugs to remove excess water from the bosy, and to treat high cholesterol levels, are also often used.
Cases associated with other general diseases such as systemic lupus erythematosis (SLE) or vasculitis will probably need treatment with drugs to suppress the immune system, including steroids and more powerful agents such as azathioprine or cyclophosphamide.

Complications

 Possible complications vary according to the type of glomerulonephritis but can include:

• Pain - Most patients with glomerulonephritis do not get pain over the kidneys, but in a few cases it can be severe.

•  Disease in other internal organs. In many patients, glomerulonephritis affects only the kidneys. However, in some cases, the immune system that damages the kidneys can also affect other parts of the body, perhaps giving a blotchy red rash on the skin or some pain in the joints. Discuss any symptoms you may have with your doctor to see if they could be related to glomerulonephritis.

• High blood pressure - this is a common complication of glomerulonephritis, because the kidneys control the level of blood pressure in the body. Many people with glomerulonephritis are prescribed blood pressure tablets. It is important to take these to protect the kidneys against further damage and also to reduce the risks of heart disease and stroke.

• Kidney failure – this is rare, but glomerulonephritis can cause so much damage to the kidneys that they fail completely, and dialysis or a kidney transplant need to be contemplated.
  Prevention

Glomerulonephritis is not generally preventable, but early diagnosis and treatment should improve the outcome. Historically, many cases of glomerulonephritis were reactions to sore throats caused by the streptococcus bacterium.
In the Ireland, this type of glomerulonephritis is quite rare, and either better living standards or the treatment of sore throats with antibiotics may be responsible. However, it should be noted that most sore throats are not caused by Streptococcus and do not require antibiotic treatment.