FSGS and IgM nephropathy: common symptoms and signs

Common symptoms and signs

The main symptoms and signs for FSGS and IgM nephropathy are similar to those in other types of nephrotic syndrome.

Swelling in the body

Children have swelling or puffiness in different parts of their body – this is called oedema. The oedema is normally around the eyes in the morning, and in the legs and feet later in the day. After a while there may be swelling throughout the day. Boys may also have oedema of the scrotum. It is pitting oedema. This means that when the affected area is gently pushed, there is a small dent for a few moments.

If your child has swelling in the body, seek medical advice as soon as possible.

In FSGS and IgM nephropathy, the swelling happens because there is too much fluid in the body’s soft tissues.

This is caused by the kidneys leaking a lot of protein, which is normally in the bloodstream, into the urine. An abnormal amount of protein in the urine is proteinuria. You cannot usually see the protein. Your child’s doctor can find proteinuria on a urine test.

A lot of the protein that is leaked is a type called albumin. Albumin helps keep fluid in the blood. Fluid moves between the blood and the body’s soft tissues, and when there is not enough albumin in the blood, fluid stays in the soft tissues.

Problems urinating

Some children urinate less often or smaller amounts.

Blood in the urine

Some children also have haematuria (blood in their urine), which happens when red blood cells leak through the kidney’s filters into the urine. Sometimes you cannot see the blood, but if there is a lot, the urine may be coloured red or dark brown (like blackcurrant squash or a cola drink).

Rare symptoms and signs

Swelling in the tummy and breathlessness 

  • A few children get a large swelling in their abdomen (tummy area). This is called ascites. It happens when fluid builds up in the area around the organs in the abdomen – the peritoneal cavity.
  • A very small number of children feel breathless. This happens when fluid builds up in the area around their lungs.

If your child has FSGS or IgM nephropathy and a very swollen tummy or feels breathless, contact your doctor as soon as possible.

Other rare symptoms

The symptoms below are occasionally found in children with FSGS or IgM nephropathy:

  • tiredness, low energy or difficulty concentrating
  • decreased appetite (not want to eat)
  • nausea (feeling sick), vomiting (being sick), or diarrhoea
  • pain in the abdomen (tummy)
  • headaches that keep coming back or that do not go away
  • pain, stiffness or swelling of the joints.


Some children have complications – health problems that happen because of the condition or its treatment. These are very rare but are more likely to happen if the oedema lasts a long time.

Risk of infections

  • Children with FSGS and IgM nephropathy are treated with medicines that suppress, or damp down, their immune system, which normally protects them from infections. They are therefore more likely to get infections such as the common cold or a urinary tract infection.
  • If your child is unwell and you are worried about an infection, contact your doctor straight away.

Other complications

If your child has any of the below contact your doctor:

  • severe pain in his or tummy and/or a fever (temperature above 38°C) – this may be a sign of an infection called peritonitis
  • swollen, red or painful leg – this may be a sign of a blood clot 
  • headaches, vomiting or blurred (fuzzy) vision – this may be a sign of hypertension (high blood pressure)
  • feeling more tired than usual, having sleep disturbances such as difficulty getting to sleep, becoming more forgetful or gaining weight – this may be a sign of low levels of thyroid hormone

Read more about complications

Peritonitis (tummy pain and fever)

Peritonitis is inflammation (like a swelling) of the peritoneum. This is a thin layer that lines the inside of the abdomen. It surrounds and supports organs such as the stomach and liver. Peritonitis is caused by a bacterial infection. Children with peritonitis have severe pain in their tummy and a fever (temperature above 38°C), and may sweat and/or seem shivery.

Thrombosis (blood clot)

In nephrotic syndrome, blood may be thicker than normal. This happens when some of the water in the blood leaks out of the blood vessels. The blood is more likely to form a blood clot (like a clump of hardened blood).

If a blood clot is large enough to block a vein, it can cause thrombosis. The leg, or occasionally another part of the body, may look swollen and may look red and feel painful.

Hypertension (high blood pressure)

Hypertension is blood pressure that is too high. In some children, this leads to headaches, vomiting or blurred (fuzzy) vision. Hypertension that lasts a long time can also increase the risk of getting other diseases in adulthood.

If your child has hypertension, he or she may need to make changes to his or her diet, or take medicines to get their blood pressure in a healthy range.

Low levels of thyroid hormone

The thyroid is a gland in the neck that makes thyroid hormone. This hormone (a chemical that is carried in the blood to send messages to other parts of the body) controls how the body uses energy. 

Some children with nephrotic syndrome have low levels of thyroid hormone in their body – this is called hypothyroidism (“hypo” means low or not enough). This causes many of the body’s functions to slow down. Some children with hypothyroidism may:

  • be more tired than usual or have sleep disturbances such as difficulty getting to sleep
  • become more forgetful
  • gain weight
  • have dry hair, skin and nails
  • have changes in mood (more sad than normal)
  • be constipated (difficulty doing a poo)
  • feel breathless
  • feel sensitive to cold 
  • get cramps in their muscles, or feel weak. 


A few children have swelling of the lining of their gut. This can cause diarrhoea.

High levels of fat in the blood

Rarely, children with FSGS and IgM nephropathy have too much of some fats in their blood – even when they eat a healthy diet and are active. This is more likely in children who have proteinuria for long periods of time.

Read more about high levels of fat in blood

Nephrotic syndrome can lead to a high level of fats in the blood, which is called hyperlipidaemia (“hyper” means too much). These fats are made in the body and are in many foods. Two types of fat are:

  • triglycerides – a high level of these is called hypertriglycideraemia 
  • cholesterol – a high level of this is called hypercholesterolaemia.

Eating a healthy diet and being active usually helps keep these fats at a healthy level. But in nephrotic syndrome, there is a lower level of some proteins, especially albumin, in the blood because they are leaked into urine. This causes the levels of fats to increase.

When the kidneys stop working suddenly

In serious cases, the kidneys stop working as well as they should, over a short period of time – this is called acute kidney injury (AKI). Some children get better after a few weeks, and some need to take medicines or have more intensive treatment.