Nephritis Dr Trisha Macnair Inflammation of one or both of the kidneys can occur due to a previous infection.

In this article

What is nephritis? Symptoms

Causes and risk factors Treatment and recovery

Nephritis is inflammation of one or both of the kidneys - the organs that filter the blood and get rid of excess fluid and unwanted chemicals. The inflammation can be caused by many different conditions.

Symptoms may develop as the disease gets worse, but as nephritis resolves completely in about 60 per cent of adults and as many as 90 per cent of children, for many it comes and goes with little disruption to their life.

The downside is that for those in whom the disease doesn't get better and instead progresses into a more severe condition, advanced kidney (renal) failure may have developed before they have had any reason to seek medical help.

Symptoms of nephritis include:

• Swelling of the tissues (initially the face and around the eyes, later more prominent in the legs)
• Reduction in urine volume
• Dark urine (contains blood which may not be visible)
• Increase in blood pressure
• Headaches
• Drowsiness
• Visual disturbances
• Tiredness and general malaise (feeling ill)
• Nausea
• In rapidly progressive disease, loss of appetite, vomiting, abdominal pain and joint pain may occur
• Chronic nephritis may go unnoticed for years until symptoms of kidney failure appear: tiredness, itchy skin, nausea and vomiting, shortness of breath

About half of those who develop acute nephritis actually have no symptoms. If symptoms do develop, they point clearly to the problem. The inflammation causes blood and protein to leak into the urine. As protein levels in the blood fall, excess fluid accumulates in the body.

Tests show protein, blood cells, and kidney cells in the urine, while a high concentration of the body's waste products of metabolism (such as urea and creatinine) may be found in the blood.

Swabs of the throat may show there's been a streptococcal infection, while blood tests may be used to check for antibodies to streptococci or other infections, or signs of an abnormal immune response.

Sometimes a small biopsy or sample of tissue is taken from the kidney to examine in the laboratory.

The causes of nephritis (or acute nephritic syndrome as the collection of symptoms is sometimes called) tend to be different in adults and children.

One of the commonest, especially in children, is after infection with the streptococcus bacteria, which leads to an immune reaction that damages the filtering units of the kidney known as the glomeruli. This condition is called post-streptococcal glomerulonephritis.

Other causes seen more frequently in children than adults include Henoch-Schönlein purpura (an inflammation of the blood vessels caused by an abnormal immune response) and haemolytic-uraemic syndrome (an abnormal immune reaction with triggers including gastrointestinal infection).

In adults, diseases that frequently underlie nephritis include vasculitis (inflammation of the blood vessels), pneumonia, abscesses, infections such as measles, mumps or glandular fever, hepatitis, and a range of different immune disorders that cause types of glomerulonephritis.

In more serious, rapidly progressive glomerulonephritis, about half of people remember having had a flu-like illness in the month before symptoms start.

The treatment of nephritis depends on the type and cause of the condition. The aim is to reduce inflammation, limit the damage to the kidneys and support the body until kidney function is back to normal.

Restriction of sodium (salt), potassium, protein and fluids in the diet may be necessary. Sometimes bed rest is advised. Steroids, or more powerful immunosuppressant drugs, may be given to reduce the inflammation.

Antibiotics may be needed too, although in many cases the infection that initially triggered the nephritis has long since gone. Medication may also be needed to control blood pressure.

In severe cases, renal dialysis may be necessary, although this may only be a temporary measure.

Adults are slower to recover than children and more likely to develop complications or progress into chronic nephritis. Acute nephritic syndrome is unlikely to recur, but if it does there's at least a one in three chance that an adult will develop what is known as 'end-stage kidney disease', leaving them in need of permanent dialysis or a kidney transplant.

This article was last medically reviewed by Dr Orlena Kerek in March 2009