Overview
Nephrotic syndrome is a group of signs that show the kidneys are leaking protein. The tiny filters in the kidneys (glomeruli) become damaged or inflamed, and large amounts of protein pass into the urine instead of staying in the blood.
Four things happen together: a lot of protein in the urine, a low level of the protein albumin in the blood, swelling (oedema), and high and other fats in the blood. In children the most common cause is minimal change disease, which most often starts between the ages of 2 and 6.
Symptoms
- Swelling, often first around the eyes (puffy eyelids), then in the legs, ankles and feet, and sometimes the tummy
- Foamy urine
- Weight gain from fluid held in the body
- Tiredness
- Poor appetite
When to see a doctor
See a doctor soon if you or your child has puffy eyes, swelling of the feet, ankles or tummy, or foamy urine. If you already have the condition, contact your doctor if swelling is not improving with treatment, or if a fever, a severe headache or much less urine than usual appears.
Causes
Nephrotic syndrome happens when something damages the filters in the kidneys. There are two broad groups of cause:
- Kidney diseases that affect the filters themselves, such as minimal change disease (the main cause in children), focal segmental glomerulosclerosis and membranous nephropathy
- Other illnesses that damage the kidneys, such as diabetes, lupus, amyloidosis, infections such as HIV and hepatitis B and C, some cancers, some inherited conditions, and some medicines, including anti-inflammatory painkillers ()
Risk factors
- Diabetes
- Lupus and other immune conditions
- Infections such as HIV and hepatitis B and C
- Taking certain medicines, such as anti-inflammatory painkillers
- Inherited (genetic) kidney conditions
Complications
Losing protein and holding on to fluid can lead to:
- Blood clots, including clots in the veins
- Infections, because the body loses some of the proteins that fight germs
- High
- Too much fluid in the body, which can strain the heart and collect in the lungs
- High and heart and blood vessel disease
- Acute or chronic kidney failure
Prevention
Nephrotic syndrome cannot always be prevented, and diet has not been shown to cause or prevent it. Treating the conditions that can lead to it may help:
- Keeping diabetes under good control
- Getting conditions such as lupus, hepatitis B and C, and HIV treated
- Asking a doctor before taking anti-inflammatory painkillers regularly
- Once diagnosed, having the pneumococcal and a yearly flu vaccine, as advised, to guard against infections
Diagnosis
A urine dipstick test can show protein in the urine. It is confirmed with a urine albumin-to-creatinine ratio test or a 24-hour urine collection. Blood tests show a low level of albumin, high and fats, and how well the kidneys are working.
To find the cause, more blood tests and a kidney may be done. A kidney , in which a small piece of kidney tissue is examined, may be needed to identify the cause.
Treatment
Treatment has two parts: easing the effects, and treating the cause. It may be lifelong, and some people have periods of followed by relapses. Options include:
- ACE inhibitors or ARBs, medicines that lower and reduce protein loss
- Water tablets (diuretics) to reduce swelling
- -lowering medicines (), if needed
- Blood thinners, usually when a clot has developed
- Diet changes as advised, usually less salt, sometimes less fat and a moderate amount of protein, and limits on fluids if swelling is a problem
- Medicines that calm the immune system, such as corticosteroids, for the causes that need them
Some people recover fully once the cause is treated, but others develop chronic kidney disease and may eventually need or a kidney transplant.
Myths and facts
Things people often say about this. Open each one to see what is true.
Myth“Swelling of the face or feet is just an allergy or too much salt, and will go away by itself.”What is true?
Fact
Swelling can have simple causes, but swelling that persists, especially with foamy urine, can mean the kidneys are leaking protein. That needs urine and blood tests. Cutting down on salt can help control swelling once nephrotic syndrome is diagnosed, but it does not cure it.
Myth“Nephrotic syndrome is caused by eating the wrong food, and a high-protein diet will replace what is lost.”What is true?
Fact
Diet has not been shown to cause or prevent nephrotic syndrome. It is caused by damage to the kidney filters, either from a kidney disease or from another illness such as diabetes or lupus. Treatment often includes a moderate amount of protein rather than a lot, so ask the doctor or a dietitian before changing the diet.
Myth“Steroids are harmful, so a child should stop them as soon as the swelling goes.”What is true?
Fact
Corticosteroids cure most children with the common form (minimal change disease), though some need to stay on them longer to prevent a relapse. Do not stop or change them without the doctor's advice, and report side effects so the plan can be adjusted.
Myth“Once the swelling has gone, the problem is cured for good.”What is true?
Fact
Nephrotic syndrome can settle, but relapses can happen, in children and in adults. Some people have periods of remission followed by relapses, which is why follow-up and urine checks continue.
Questions to ask your doctor
Tick the ones you want answered and take them with you.
Common questions
Is nephrotic syndrome curable?
It depends on the cause. Steroids cure most children with the common form, though relapses can happen. Some adults recover completely once the cause is treated, while others have repeated relapses or develop long-term kidney damage. A kidney specialist can explain what to expect.
Is nephrotic syndrome the same as kidney failure?
No. Nephrotic syndrome means the kidneys are leaking protein. Kidney failure means they can no longer clean the blood well. In some cases nephrotic syndrome can lead to kidney failure over time, which is why follow-up matters.
Do I need a special diet?
Diet does not cause or prevent nephrotic syndrome. Once swelling appears, a doctor may advise limiting salt and sometimes fluids and fat. Do not change the diet or add protein supplements on your own. Ask the doctor or a dietitian.
Why does nephrotic syndrome raise the chance of infections and clots?
The kidneys lose proteins that help fight germs, so infections are more likely. The condition also raises the chance of blood clots. That is why vaccines are advised, and why a swollen painful leg, breathlessness or fever should be reported promptly.
