What is steroid-resistant nephrotic syndrome (SRNS)?
Nephrotic syndrome is a rare kidney condition that causes too much protein to be lost in the urine and too much water to be retained in the body.
In most cases, nephrotic syndrome can be treated with steroids. It is then known as steroid-sensitive nephrotic syndrome (SSNS).
However, for some people, steroids do not work. In those cases, the condition is known as steroid-resistant nephrotic syndrome (SRNS).
In rare cases, steroids work at first and then stop working, so the diagnosis changes from SSNS to SRNS.
Nephrotic syndrome affects around 10,000 people in the UK a year. SRNS affects around one in 10 children with nephrotic syndrome and four in 10 adults with nephrotic syndrome.
SRNS is also sometimes known as focal segmental glomerulosclerosis (FSGS).
What are the signs and symptoms of SRNS?
Common symptoms of SRNS include:
- protein in the urine (proteinuria) – this is likely to only be seen under a microscope or when tested by dipping a specially treated paper strip into your urine (urine dipstick). However, if there is a lot of protein, the urine may look frothy.
- swelling or puffiness (oedema) – this can develop in different parts of the body, especially around the eyes and ankles. Swelling around the eyes tends to be worse first thing in the morning and improve as the day goes on whereas ankle swelling is usually worse in the evenings. The swelling is soft and puffy and leaves a dent if you press on it. There is no pain associated with the swelling. It is not an allergic reaction but is caused by the kidneys retaining too much water.
- increased risk of infection
- low blood pressure.
What causes SRNS?
Nephrotic syndrome occurs when the tiny filters in the kidney (glomeruli) are damaged. This causes them to leak protein and retain excess water. Over time this can cause kidney damage.
Other substances can also be lost through the damaged filters, including antibodies that help prevent infections. Without these, people with SRNS are more vulnerable to illnesses and infections.
Hormones and vitamins can also be lost, which can delay growth in young children.
SRNS appears to be caused by a genetic mutation in around one in three people with the condition. The cause for the other cases is currently unknown.
How is SRNS diagnosed?
Nephrotic syndrome is diagnosed by a urine test that will show very high levels of protein.
The exact type of nephrotic syndrome can be diagnosed by a kidney biopsy or by treatment with steroids (prednisolone). If the steroids work, the condition is known as steroid-sensitive nephrotic syndrome (SSNS). If they do not work after four to six weeks, it is steroid-resistant nephrotic syndrome (SRNS).
Genetic testing may also be offered.
Does SRNS affect other parts of the body?
During flare-ups of SRNS (when swelling occurs), people are more at risk of infections or of developing blood clots, particularly in the veins of the legs (thrombosis).
Does SRNS run in families?
A genetic abnormality is found in around one in three people with SRNS, covering more than 50 different genes. The precise details of any inheritance patterns are still being investigated.
How is SRNS treated?
There is currently no direct cure for SRNS, so treatment aims to control the symptoms and protect the kidneys for as long as possible.
As steroids do not work to control the nephrotic syndrome in SRNS, angiotensin‐converting enzyme (ACE) inhibitors or angiotensin receptor blockers (ARBs) are usually prescribed to reduce the proteinuria.
Water tablets are also likely to be prescribed to reduce the swelling.
Blood pressure medication may also be prescribed and/or aspirin to reduce the chance of developing blood clots.
Dietary changes may also be recommended, including a low-salt diet and vitamin supplements. This should only be undertaken with advice and monitoring by a specialist kidney dietitian. Babies with SRNS may need to be tube fed to make sure they get enough nutrition to grow and develop.
Some people with SRNS recover or go into remission. However, for most people the condition will get worse over time and will lead to kidney failure and the need for dialysis and/or a transplant.
SRNS can reoccur in the new kidney. This is less likely if the SRNS is due to a genetic mutation and more likely if the person initially had SSNS and then developed SRNS.
Where can I get more information or support about SRNS?
For more information on SRNS including its diagnosis, symptoms and treatment, visit Nephrotic Syndrome Trust.
Publication date: 11/2023
Review date: 11/2026
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