Post-infectious glomerulonephritis (PIGN)

Post-infectious glomerulonephritis (PIGN)

Also known as post-streptococcal glomerulonephritis (PSGN)

PIGN causes inflammation (swelling) in the kidneys. Children with PIGN have blood and protein in their urine, and may have swelling in their body, especially around their face and legs. PIGN may lead to other complications, including high blood pressure (hypertension).

This condition happens in a few children, after they have an infection – usually in the throat, nose or sinuses, or occasionally the skin.

Many children with PIGN get better after a few weeks, without treatment. A few need to take medicines or have more intensive treatment.

About the urinary system and kidneys

The urinary system gets rid of things that the body no longer needs, so that we can grow and stay healthy.

  • The kidneys are bean-shaped organs. They filter blood to remove extra water, salt and waste in urine (wee). Most of us have two kidneys. They are at the back on either side of our spine (backbone), near the bottom edge of our ribs.
  • The two ureters are long tubes that carry urine from the kidneys to the bladder.
  • The bladder is a bag that stores urine until we are ready to urinate (wee).
  • The urethra is a tube that carries urine from the bladder to the outside of the body.

More about the urinary system and kidneys

Symptoms and complications

Symptoms and signs

Some children with PIGN do not have any symptoms and signs, especially in the early stages of the disease. Common symptoms and signs include:

  • blood in the urine (haematuria) – you cannot always see the blood, but if there is a lot, the urine may be coloured red or dark brown (like a cola drink)
  • protein in the urine (proteinuria) – you cannot usually see the protein, but sometimes it can make the urine look frothy. but It can be found on a simple urine test
  • urinating less often or smaller amounts
  • swelling or puffiness in different parts of the body, especially around the eyes, legs and feet – this is called (oedema)
  • rarely, swelling in the adbomen (tummy), or breathlessness 


Some children have complications – health problems that happen because of the condition – including those below.

  • PIGN may lead to blood pressure that is too high (hypertension).
  • Occasionally, the condition gets worse quickly and the kidneys work less well than normal – this is called rapidly progressive glomerulonephritis (RPGN)
  • RPGN is one cause of acute kidney injury – when the kidneys quickly stop working as well as they should, over a short time.

More about symptoms and complications


About glomerulonephritis

Post-infectious glomerulonephritis (PIGN) is a type of glomerulonephritis, a group of conditions that affect the kidneys.

Inside the kidneys, there are many tiny filters called glomeruli. They help to remove extra water, salt and waste, which are passed out of the body as urine. They also make sure the body keeps what it needs, such as blood cells, protein and other important chemicals.

In glomerulonephritis, the glomeruli become inflamed (swollen) or damaged. This causes both blood and protein to leak into the urine.

About PIGN

PIGN happens in a few children after they have an infection – usually in the throat, nose or sinuses, or occasionally the skin. Most children get better from these infections, but a small number get glomerulonephritis about 4–6 weeks later.

These infections are often, though not always, caused by a bacterium (germ) called Streptococcus.

When glomerulonephritis appears after an infection from Streptococcus, the condition is called post-streptococcal glomerulonephritis (PSGN). We will refer to the condition as PIGN throughout this topic.

PIGN is an acute condition, which means that it starts suddenly.

PIGN can happen in people of all ages, including children. It is not always clear why a few people get this condition after an infection. Doctors think it is caused by problems with the immune system, which normally protects the body against disease and infection.

More about causes

Tests and diagnosis

Your child’s doctor can diagnose (identify) PIGN by doing some tests. If your child has certain symptoms or signs, such as red or brown urine, your doctor may arrange a urine test. Your doctor will speak with you and your child about the symptoms and do a physical examination. Your child may also need other tests, such as blood tests and an ultrasound scan.

Your doctor may recommend a kidney biopsy. A tiny piece of one kidney is removed from the body with a needle. This is examined under special microscopes. Special medicines are used so your child does not feel any pain or can sleep through the procedure.

More about tests and diagnosis


Where will my child be treated?

Your child will probably be admitted to hospital for a few days. Some children are referred to a paediatric renal unit, a special unit for children with kidney problems, which may be in a hospital different to your own. Your child will be looked after by a paediatric nephrologist, a doctor who treats children with kidney problems.

About treatment

The healthcare team will check how your child’s kidneys are working, test how much he or she is weeing, and measure his or her blood pressure. They will support you and your family throughout the treatment. Your child can go home when the doctor thinks that his or her health is stable. Your child will need to go back to the hospital clinic for treatment or follow-up.

Many children do not need special treatment, but may need to make temporary changes to what they eat and drink. Some children need medicines to get rid of the infection that caused PIGN, or to treat complications.

If another health condition is causing PIGN, this may need special treatment.

What happens if my child does not get better?

If your child’s kidneys stop working properly, he or she may need special treatment.

This may include dialysis, which uses special machines to help do the job of healthy kidneys.

It is important that your child follows any treatment plan outlined by your doctor. More about treatment

About the future

All children with PIGN need to go back to the hospital or clinic for follow-up appointments, to check for any health problems.

Long-term effects

Most children with PIGN get better after a few weeks without any treatment, and there are no long-term problems with their kidneys.

A few children will have long-term problems with their kidneys. These children may need further care. They will need to go back to the hospital or clinic for regular appointments.

More about the future