Your doctor will try to find out what is causing the glomerulonephritis in your child. Occasionally it is not clear why the glomeruli are inflamed or damaged.
What happens in the kidneys
Inside each kidney are about a million tiny filters called glomeruli. They help to remove extra water, salt and waste, which are passed out of the body in 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.
Read more about how the kidney works and glomerulonephritis
How the kidney works
Inside each kidney, there are about one million nephrons. Each nephron is made up of a glomerulus (when we talk about more than one glomerulus, we say glomeruli), and a renal tubule.
- Each glomerulus acts like a sieve, helping to remove extra water and waste from the body, and holding on to blood cells and protein, which the body needs.
- Blood flows into the kidneys and to each glomerulus.
- Most of the water and some other substances in the blood pass through the glomeruli.
- This liquid flows into the renal tubule. Most of this liquid moves back into the bloodstream. The rest of it becomes urine.
- The urine leaves the kidney by the ureters and goes into the bladder, where it is stored until we are ready to go to the toilet.
About the urinary system and kidneys – what the kidney does
About the name
Nephritis means inflammation, or swelling, in the kidneys. Glomerulonephritis is specifically about inflammation of the glomeruli.
Immune system
Germs
The immune system protects the body against germs such as bacteria and viruses that can cause illness. These germs can enter the body in lots of ways, such as by the nose and throat or the urinary system. If we get a cold or flu, this means that a virus germ has got into the body and started to infect some of our body’s cells.
Germs have special ‘markers’ that are different from the markers on our own body’s cells. This means that the immune system can recognise that they are germs and kill them. We often feel sick for a few days or a few weeks while this is happening.
Parts of the immune system
The immune system has many different ways to protect the body against disease. Some of the parts include those listed below.
- White blood cells are living cells in the blood. Often, the number of white blood cells found in a blood test can give information about someone’s immune system. The two main types of white blood cells in the immune system are neutrophils and lymphocytes.
- Antibodies or immunoglobulins recognise the germs that have come into the body, and can bind (stick) to them. There are five types: immunoglobulin A (IgA), immunoglobulin D (IgD), immunoglobulin E (IgE), immunoglobulin G (IgG) and immunoglobulin M (IgM).
- The complement system is made up of other proteins that float in the blood. These proteins work with (complement) other parts of the immune system to help kill germs or cells infected by germs. Normally, the body controls when complement is activated, so it does not attack the body itself.
When the immune system does not work properly
Sometimes the immune system does not work as expected and can cause problems. For example, sometimes the immune system cannot recognise the body’s own cells and may attack them as if they were invaders like germs
After infection
Most children with glomerulonephritis get it after an infection – usually affecting the throat, nose or sinuses, or occasionally the skin. This type of glomerulonephritis is called post-infectious glomerulonephritis (PIGN). If the infection is caused by a type of bacteria called Streptococcus, it may be called post-streptococcal glomerulonephritis (PSGN).
Most children recover from these infections. However, a small number of children get glomerulonephritis after about two weeks from the start of the infection. It is not always clear why a few children get this condition after an infection, though it may be because of problems with their immune system.
The immune system
Many germs – including bacteria and viruses – can make us sick if they get into the body. The immune system can kill these germs. However, if the immune system is not working properly, it can start to cause problems.
Types of glomerulonephritis linked to the immune system
- IgA nephropathy, or Berger disease: proteins called IgA, which are part of the immune system, get trapped in the glomeruli.
- Henoch–Schönlein purpura (HSP): IgA settles on blood vessels throughout the body. Children with HSP have a rash, and may have joint pain and tummy pain. Some cases of HSP affect the kidneys, causing glomerulonephritis.
- Membranoproliferative glomerulonephritis (MPGN): a protein called complement, which is also part of the immune system, gets trapped in the glomeruli. This is also called mesangiocapillary glomerulonephritis (MCGN).
Read more about the immune system
Germs
The immune system protects the body against germs such as bacteria and viruses that can cause illness. These germs can enter the body in lots of ways, such as by the nose and throat or the urinary system. If we get a cold or flu, this means that a virus germ has got into the body and started to infect some of our body’s cells.
Germs have special ‘markers’ that are different from the markers on our own body’s cells. This means that the immune system can recognise that they are germs and kill them. We often feel sick for a few days or a few weeks while this is happening.
Parts of the immune system
The immune system has many different ways to protect the body against disease. Some of the parts include those listed below.
- White blood cells are living cells in the blood. Often, the number of white blood cells found in a blood test can give information about someone’s immune system. The two main types of white blood cells in the immune system are neutrophils and lymphocytes.
- Antibodies or immunoglobulins recognise the germs that have come into the body, and can bind (stick) to them. There are five types: immunoglobulin A (IgA), immunoglobulin D (IgD), immunoglobulin E (IgE), immunoglobulin G (IgG) and immunoglobulin M (IgM).
- The complement system is made up of other proteins that float in the blood. These proteins work with (complement) other parts of the immune system to help kill germs or cells infected by germs. Normally, the body controls when complement is activated, so it does not attack the body itself.
When the immune system does not work properly
Sometimes the immune system does not work as expected and can cause problems. For example, sometimes the immune system cannot recognise the body’s own cells and may attack them as if they were invaders like germs.
Other conditions or infections
Sometimes glomerulonephritis is caused by another condition or infection.
- Systemic lupus erythematosus (SLE, or lupus): the immune system does not work properly and attacks different parts of the body, sometimes including the kidneys.
- ANCA-positive nephritis: blood vessels in the kidney and other parts of the body become inflamed. ANCA is a type of antibody – instead of killing germs as other antibodies do, ANCA attack the body’s own tissues and cells.
- Other infections: a small number of children who have infections such as HIV, hepatitis B or hepatitis C, get glomerulonephritis.
Hereditary causes
Rarely, glomerulonephritis is hereditary, which means that it is inherited from the mother and/or father.
- Alport syndrome is a very rare condition, which may also be called hereditary nephritis. Children are born with an abnormality (problem) in the walls of the blood vessels that make up their glomeruli. These children may also have problems with hearing or seeing. The complications are usually more serious in boys than in girls.
Will it affect other family members?
Most types of glomerulonephritis do not run in families. If one of your children has glomerulonephritis, it is unlikely that another of your children or family members will get it.
If your child has a hereditary form of glomerulonephritis, such as Alport syndrome, your doctor will give you more information.