Steroid Resistant Nephrotic Syndrome – Patient Information
- How the illness affects people
Steroid resistant nephrotic syndrome (SRNS) is a rare kidney condition. It causes excess fluid to be retained in the body which causes swelling (oedema). This is most common in the face, eye lids, and ankles. Facial swelling is usually worse in the mornings and ankle swelling worse in the evenings or after standing.
The swelling in Nephrotic Syndrome is soft and puffy so that if you press on it lightly it leaves a dent. With more extensive fluid retention, swelling may affect the abdomen and hands, and cause a feeling of tightness. Excess fluid inside the abdomen is known as ascites. The extra fluid in the body increases body weight.
Nephrotic Syndrome makes people vulnerable to infections while they are swollen. It can also increase their risk of developing blood clots (thrombosis), mostly affecting the veins of the legs.
If SRNS develops very soon after birth it is known as congenital nephrotic syndrome. This implies a genetic cause and other family members may be affected in some way.
- What can be done about it?
The first step is to confirm the diagnosis. There are many reasons for fluid to be retained in the body and cause swelling. In Nephrotic Syndrome it is due to very heavy losses of proteins such as albumin in the urine (proteinuria, albuminuria). A urine test will confirm this.
Some people with Nephrotic Syndrome, particularly children, are given treatment with corticosteroids (for example prednisolone) as a first step to see if they will respond. By definition Steroid Resistant Nephrotic Syndrome (SRNS) is the diagnosis that applies to those patients who not respond to steroids. This occurs in approximately 10-20% of children and 40% of adults with Nephrotic Syndrome.
A kidney biopsy may help to distinguish between these two broad types of nephrotic syndrome.
Increasingly genetic tests are used to further define the diagnosis of SRNS. The Nephrotic Syndrome RDG have helped to develop a ‘Gene panel’ test which has been approved for NHS use. Any patient with SRNS can be tested by their clinician in a rapid manner not previously possible, via the Bristol Genetics Lab. A huge advantage is that this can test all known genes in one simple blood test – something that would not have been possible using previous technology. Hundreds of patients have now been tested, not just from the UK but also worldwide, and the test continues to be improved in terms of speed and scope.
At present a genetic abnormality can be found in 30-40% of patients with SRNS (McCarthy & Saleem, 2011). Some of these abnormalities are inherited and other members of the family will carry the abnormal gene and may be affected themselves. Genetic testing can now be performed for most genes known to cause SRNS. For more information click here.
In SRNS other treatments that suppress the immune system are often tried to correct the underlying process. Benefit is observed in about a third of patients but these drugs also have side effects, such as increasing the risk of infection. Patients with a genetic mutation are less likely to respond to immunosuppressive drugs (McCarthy & Saleem, 2011).
A lot can be done to help control the symptoms of Nephrotic Syndrome and prevent complications. For example diuretic treatment and a low salt diet can usually control the swelling. Certain types of blood pressure lowering medicines known as Angiotensin Converting Enzyme (ACE) inhibitors or Angiotensin Receptor Blockers (ARB) can be used to reduce the amount of protein that is lost through the kidneys. This also helps prevent swelling.
SRNS patients are at risk of infections and this can be reduced through immunizations and the careful use of antibiotics.
Detailed dietary advice and support is very important for SRNS patients, especially children (see Dietary Needs). This attempts to make up for the loss of important proteins that are wasted in the urine. Small babies with SRNS may need to be tube fed to make sure that they receive enough nutrition to grow. Patients may also need to take vitamin supplements and thyroid hormone as these are also lost in the urine.
A small daily dose of aspirin may be considered to reduce the risk of developing thrombosis.
There is no known cure for SRNS. Although a few patients do show spontaneous improvement or remission, for many it is a progressive condition that can lead to kidney failure. As a patient approaches chronic kidney disease stage 4 (CKD 4) plans will need to be put in place for dialysis or transplantation.
If a patient with SRNS has a kidney transplant, there is a 30-50% risk that the disease will come back in the new kidney. The risk of recurrence is lower if SRNS is due to a genetic mutation (McCarthy & Saleem, 2011). The risk of recurrence is higher if the patient was initially steroid sensitive and developed steroid resistance later on (Ding et al, 2014). If the condition recurs it requires further immunosuppressive treatment.
- Other peoples’ experiences
The NephCure website contains many personal stories, including those from patients with SRNS.
Patient Information Days
The latest Nephrotic Syndrome Patient Information Day was held in Bristol on the 29th March 2017.
Previous events were held in Manchester (2016) and Birmingham (2015) For further details of these events please visit the Nephrotic Syndrome Trust.
- Patient support group
The Nephrotic Syndrome Trust (NeST) aims to raise money for research into the causes, treatment and hopefully a cure for nephrotic syndrome. They have set up a number of closed Facebook groups to help those with Nephrotic Syndrome, their family members and carers to support each other in their local area.
The NephCure Foundation educates the public and raises awareness of Nephrotic Syndrome around the world.
- How the disease works
The kidneys filter the blood plasma through microscopic specialised blood vessels (glomeruli). These filters normally allow water and small molecules like salt and waste products to cross over from the plasma into a tubule. After processing, the filtered fluid finally leaves the body as urine. Healthy glomeruli are very efficient at preventing larger molecules like albumin from crossing from plasma to urine. In SRNS patients the structure and function of the kidney’s filters are damaged. This allows proteins to leak out of the bloodstream and into the urine.
The watery fluid of the blood stream (plasma) is rich in proteins, especially albumin. If you know that an egg white is chicken albumin dissolved in water, you get the picture of plasma containing human albumin. When the kidneys filter the plasma they normally keep the albumin and other proteins and don’t let them cross over into the urine. In Nephrotic Syndrome this fails to happen so albumin pours into the urine and is lost. The body tries to make more albumin and other proteins but it is never enough, and the level of albumin in the blood falls.
In SRNS extra fluid accumulates in the tissues of the body. Normally the tiny blood vessels of the body allow water from the blood stream to move out into the tissues and back again. There is a fine balance to this process.
In the little blood vessels of the body, albumin helps to prevent fluid from leaking out of the plasma and into the body’s tissue. So when the level of albumin is low, fluid builds up in the soft tissues of the body.
The kidneys respond to this by retaining even more water. This makes the swelling worse.
As well as albumin, other proteins are also lost into the urine in SRNS. Immunoglobulins help ward off infections. If these are lost the risk of getting an infection increases. Proteins essential for transporting important substances around the body can also be lost. Hormones and vitamins carried on these proteins are lost with them. This is why some SRNS patients need hormone or vitamin supplements.
The level of cholesterol and fat in the blood stream can be very high in SRNS patients. This is also because of the protein abnormalities.
The original problem in SRNS lies in the glomeruli in the kidney. If the structural problem is severe enough, the glomeruli may be permanently damaged. If enough glomeruli are lost, the overall function of the kidneys will decline.
- What’s new? Opportunities for research and development
The Nephrotic Syndrome Rare Disease Group (RDG) is working with international partners with the aim of finding new and improved treatments, and to empower patients. To do this the RDG is registering patients with this condition in the National Renal Rare Disease Registry (RaDaR). The database will be used to find suitable participants for future research trials into the effectiveness of new treatments. If you are interested in finding out more about the registry (RaDaR) or the activity of the RDG please visit the Nephrotic Syndrome RDG page.
Researchers are currently investigating the causes of Nephrotic Syndrome. They are looking for better forms of diagnosis and treatment. The research uses new cell and molecular technologies to investigate the particular cell (podocyte) that is responsible for the kidney’s ability to filter proteins, under the National Study of Nephrotic Syndrome (NephroS). For more information please contact the Nephrotic Syndrome RDG.
Written by the Nephrotic Syndrome Rare Disease Group