Nephrotic syndrome: symptoms, causes, treatment and children

Nephrotic syndrome is most often seen in young children. The NHS says it is usually first diagnosed in children aged between 1 and 6 years old and tends to be more common in those with an Asian background. Kidney Care UK says steroid-sensitive nephrotic syndrome affects around nine in ten children with nephrotic syndrome.

For most children the outlook is good. The NHS says that most children with nephrotic syndrome respond well to steroids and are not at risk of kidney failure, and that relapses become less frequent as they get older and often stop by their late teens. A small number of children have inherited (congenital) nephrotic syndrome, which usually carries a poorer outlook. The NHS says they may eventually have kidney failure and need a kidney transplant.

Because children are prone to infection and to blood clots during relapses, the NHS gives families specific advice: have the pneumococcal vaccine, avoid live vaccines such as MMR, chickenpox and BCG while taking medicines to control symptoms, and ask for an urgent GP appointment or NHS 111 help if a child is unwell, has a high temperature or has diarrhoea and is being sick, or has been in contact with chickenpox or measles when not known to be immune.

The NHS describes four main problems. Swelling occurs because low blood protein lets fluid move from the bloodstream into body tissues; it is usually noticed first around the eyes, then the lower legs and the rest of the body. Infection risk rises because antibodies are lost in the urine. The urine may become frothy when it contains a lot of protein, and children may pass less urine than usual during a relapse. Finally, blood clots become more likely because proteins that prevent clotting leak out, and the blood becomes more concentrated during a relapse.

Kidney Care UK adds a useful practical detail: swelling around the eyes tends to be worse first thing in the morning and improve through the day, while ankle swelling is usually worse in the evening. The swelling is soft, painless and leaves a dent if pressed, and it is caused by the kidneys retaining water rather than by an allergy. Kidney Care UK also lists anaemia and low blood pressure among possible features.

• Puffy eyelids, particularly in the morning.

• Swollen ankles and legs as fluid builds up.

• Frothy urine, and sometimes passing less urine.

• Frequent or severe infections.

• A painful, swollen leg or sudden breathlessness can signal a blood clot and needs urgent care.

Steroids are the main treatment. The NHS says that children diagnosed for the first time are normally prescribed at least a 4-week course of prednisolone followed by a smaller dose every other day for 4 more weeks, and that most respond with protein disappearing from the urine and swelling going down within a few weeks. This period is called remission. Short courses usually cause no serious or lasting problems, though increased appetite, weight gain, red cheeks and mood changes can occur. Doses are always set by the kidney team and should not be altered at home.

Other treatments support the steroid. Diuretics help remove fluid, penicillin may be given during relapses to reduce infection risk, and the NHS suggests cutting salt to limit swelling. Children are advised to have the pneumococcal vaccine, and live vaccines such as MMR, chickenpox and BCG should not be given while taking medicines to control symptoms. If steroids cause significant side effects or cannot maintain remission, other medicines may be used. The NHS lists levamisole, cyclophosphamide, ciclosporin, tacrolimus, mycophenolate and rituximab, and Kidney Care UK mentions the last three in this context. Severe cases may be admitted for albumin infusions.

Kidney Research UK says treatment can be given to deal with the symptoms, complications and causes, and that it varies with the underlying cause. Besides diuretics, salt restriction, antibiotics, steroids and immunosuppressants, it lists ACE inhibitors and ARBs to reduce the pressure in the filters and so reduce protein loss, anticoagulant treatment to reduce the risk of clots, and cholesterol-lowering drugs if the syndrome is expected to last a long time. It says some people respond well to one course of steroids, others need repeated courses and others may not respond at all.

Each kidney contains about a million tiny filters called glomeruli. Kidney Care UK explains that nephrotic syndrome occurs when these filters are damaged, so that they leak protein and the body keeps excess water. Other substances can also leak, including antibodies that help prevent infections, and in young children hormones and vitamins, which can lead to delayed growth.

It is a syndrome, a collection of features, rather than a single disease: heavy protein loss in the urine, a low level of albumin in the blood and swelling. The cause behind those features differs between patients, which is why the condition is looked at differently in children and adults.

In children the NHS says most have minimal change disease, where the kidneys look normal or nearly normal under an ordinary microscope, and its cause is unknown. Nephrotic syndrome can also occur as a result of another kidney problem or condition, which the NHS says tends to be more common in adults. Examples it lists are glomerulosclerosis (scarring inside the kidney), glomerulonephritis (inflammation inside the kidney), infections such as HIV or hepatitis, lupus, diabetes, sickle cell disease and, very rarely, certain cancers such as leukaemia, myeloma or lymphoma.

Kidney Care UK says the exact cause is not always known; it can follow an illness or infection or be part of another condition such as membranous nephropathy. There is likely to be a genetic basis in some cases. A small number of children have inherited (congenital) nephrotic syndrome, which the NHS says usually carries a poorer outlook and may eventually lead to kidney failure.

The NHS says nephrotic syndrome can usually be diagnosed by dipping a dipstick into a urine sample, which changes colour if there is a lot of protein, and a blood test showing a low level of albumin confirms the diagnosis. A kidney biopsy, in which a very small sample of kidney tissue is removed with a needle, may be needed when initial treatment does not work. Kidney Care UK adds that the exact type can be established by biopsy or by response to steroids: if steroids work it is steroid-sensitive (SSNS), and if there is no response after four to six weeks it is steroid-resistant (SRNS). Genetic testing may be offered.

In adults, doctors look harder for an underlying cause, which may involve additional blood tests and a biopsy. The linked test guides explain the basic blood and kidney-function tests used.

Most children have periods of remission followed by relapses, which the NHS says often become less frequent with age and usually stop by the late teens. Kidney Care UK says around one in three people with steroid-sensitive disease need only one round of treatment and the condition never returns, while others have repeated relapses, often triggered by an infection or a cold.

Home monitoring is a major part of care. The NHS describes testing the first urine of the day with a dipstick, writing the result in a diary and taking it to clinic. A reading of 3+ protein or more on three days in a row indicates a relapse, and the family should follow the specialist team's plan, which usually involves restarting steroids or making contact with the team. The NHS advises seeking an urgent GP appointment or NHS 111 help if a child is unwell, has a high temperature, has diarrhoea and vomiting, or has been in contact with chickenpox or measles when not known to be immune.

The NHS says you may be advised to reduce the amount of salt in your child's diet to prevent further water retention and oedema, which means avoiding processed foods and not adding salt to food. Kidney Research UK also lists dietary advice, such as restricting salt and avoiding excessive fluid intake, among the treatments that can deal with symptoms and complications.

The kidney team or a dietitian will give advice that suits the individual, including whether any fluid limit applies, so follow their instructions rather than a general rule.

The NHS says to ask for an urgent GP appointment or get help from NHS 111 if your child has come into contact with someone who has chickenpox or measles and your doctor has told you that your child is not immune, if they are unwell or have a high temperature, or if they have diarrhoea and are being sick.

Blood clots are a recognised risk. The NHS says important proteins that help prevent clotting can be passed out in the urine and that the blood becomes more concentrated during a relapse. A painful, swollen leg, sudden breathlessness or chest pain needs emergency help: call 999 or go to A&E.

Kidney Care UK says steroid-sensitive disease affects around nine in ten children and six in ten adults with nephrotic syndrome. Severe kidney damage needing dialysis or transplant is very rare in that group. For congenital disease, the NHS describes frequent albumin infusions, regular clinic review of blood pressure, growth and kidney function, and sometimes dialysis or a kidney transplant.

On the NHS, children are usually referred to a paediatric nephrologist and adults to a kidney specialist. Private nephrology consultations exist for second opinions and monitoring. Biopsy and drug costs differ, so ask for an itemised estimate, and share records so tests are not repeated unnecessarily.