Nephrotic syndrome: symptoms and complications

Nephrotic syndrome: symptoms and complications

Swelling in the body

Children with nephrotic syndrome 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 in the scrotum.

It is pitting oedema - 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.

Why the oedema happens

In nephrotic syndrome, 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 blood, into urine. When there is more protein in the urine than normal, this is called proteinuria. You cannot usually see the protein, but if there is a lot urine may look frothy. Your doctor can find proteinuria on a urine test.

If there is enough protein in the urine to cause nephrotic syndrome, this is called nephrotic-range proteinuria.

There are different types of protein in the blood. The most common type 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. When there is not enough albumin in the blood, fluid stays in the soft tissues.

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 around their lungs.

If your child has nephrotic syndrome and a very swollen tummy or feels breathless, seek medical advice as soon as possible.

Other rare symptoms

A few children with nephrotic syndrome may also:

  • feel tired, have low energy or have difficulty concentrating
  • have a decreased appetite (not want to eat)
  • have nausea (feel sick) or vomit (be sick), or have diarrhoea
  • have pain in their abdomen (tummy).


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

Risk of infections

Nephrotic syndrome is treated with steroid medicines, which make the immune system less active. This means it is more likely for children to get infections.

If your child is unwell and you are worried about an infection, contact your doctor straight away.

Acute kidney injury

Rarely, the kidneys stop working as well as they should – this is called acute kidney injury (AKI). In nephrotic syndrome, this may happen when the body has a lower volume of blood than normal – this is called hypovolaemia.

Some children with AKI get better after a few weeks, and some need to take medicines or have more intensive treatment.

Other complications

If your child has any of the below, seek medical advice:

  • severe pain in the tummy or a fever (temperature above 38°C) – if your child sweats more than usual /or is shivery – this may be a sign of an infection called peritonitis
  • swollen, red or painful leg – this may be a sign of a blood clot, when blood clumps together
  • 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, a chemical in the body.


Peritonitis is a bacterial infection in the peritoneum - this is a thin layer that lines the inside of the abdomen (tummy). It surrounds and supports organs such as the stomach and liver. Tell your doctor if your child has:

  • severe pain in the tummy
  • fever (temperature above 38°C) – if your child sweats more than usual /or is shivery.

Thrombosis blood clots

Blood may form clots, or clumps, in the veins. This may cause a condition called thrombosis, especially in the veins of the leg. This may cause the leg to look more swollen and there may be pain and redness. Blood is more likely to clot as it is thicker than normal as some of the liquid normally in the veins has leaked out and has caused the oedema.

High level of fats in the blood

Some children have a high level of type of fat, cholesterol, especially if their nephrotic syndrome is chronic (lasts a long time). A high level of cholesterol is hypercholesterolaemia (“hyper” means too much). If the nephrotic syndrome goes away, the levels of cholesterol return back to normal. If it doesn’t and the cholesterol level remains high, this can be treated with special medicines that lower the cholesterol level. Eating a healthy diet and being active usually helps keep these fats at a healthy level.

Low thyroid hormone

The thyroid is a gland in the neck which makes thyroid hormone. This hormone (a chemical that is sends messages to other parts of the body) controls how the body uses energy. Some children low levels of thyroid hormone in their body, especially if their nephrotic syndrome is chronic. This is called hypothyroidism (“hypo” means low or not enough), and 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 the 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.