What is focal segmental glomerulosclerosis (FSGS)?
Focal segmental glomerulosclerosis (FSGS) is a medical term for a family of diseases involving damage to the glomeruli (the tiny filters in the kidney).
The damage causes scarring to the glomeruli which stops them from working properly and allows protein to leak through into the urine – a condition known as nephrotic syndrome.
FSGS can affect children and adults. In some people, FSGS may stop on its own but for others, if left untreated it can lead to kidney failure and the need for dialysis or transplantation.
Causes of focal segmental glomerulosclerosis (FSGS)
Focal and segmental glomerulosclerosis (FSGS) can be caused by inherited diseases or by an immune dysfunction, where a part of the body’s immune system is over-active in a way that attacks the glomeruli. Sometimes the cause of FSGS is unknown – this is referred to as primary or idiopathic FSGS.
Focal segmental glomerulosclerosis (FSGS) symptoms
Some people may not have clear symptoms and only discover that they have higher than normal amounts of protein in their urine (proteinuria) after routine tests.
In other cases, high levels of protein loss and fluid retention can cause puffiness (oedema) around the eyes, stomach, feet and legs, and weight gain – this is known as nephrotic syndrome. Large amount of protein loss may also cause urine to appear foamy.
If kidney function is very low symptoms could include tiredness and lack of energy, itching and muscle cramps.
Depending on the cause, some people with FSGS may experience:
- High blood pressure – which needs to be controlled to protect the kidneys from further damage and to reduce the risk of heart disease and stroke.
- High cholesterol – which may need to be controlled with a special diet and cholesterol lowering drugs.
- Low thyroid hormone levels – this can be due to loss of thyroid hormone via the kidneys and is controlled by thyroid hormone supplements.
Focal segmental glomerulosclerosis (FSGS) diagnosis
Kidney biopsy
This medical procedure requires removal of small samples of the kidney to look at under a microscope in order to look at the how much damage has happened and possible causes.
Blood and urine tests
These will be performed to check kidney function and look for the presence of protein in your urine.
If FSGS is suspected, further blood tests may be needed to help find the cause.
Genetic tests
Tests may be carried out to see if your FSGS is due to a gene abnormality, which can be inherited within a family. A kidney specialist will be able to give advice about the chances of family members being affected, and whether screening should be offered to them.
Focal segmental glomerulosclerosis (FSGS) treatment
Treatment depends on the cause and severity of FSGS. Some examples of treatments include:
Steroids
Steroids to treat the symptoms of nephrotic syndrome and diuretics (water tablets) to reduce oedema
Immunosuppressants
These are drugs that dampen down the immune system and may be used to treat steroid-resistant strains of FSGS and nephrotic syndrome
Other medications
Medicines such as angiotensin-converting-enzyme (ACE) Inhibitors and angiotensin receptor blockers (ARBs) may be prescribed to control blood pressure and protein loss
Treating kidney failure resulting from FSGS
- Kidney removal
- Dialysis may be needed if the kidneys are no longer able to function well (link to our pages)
- Kidney transplantation may also be considered, but some types of FSGS may come back in the new kidney. Your healthcare professional can provide further details on this.
Resources about focal segmental glomerulosclerosis (FSGS)
If you have any questions or concerns about your FSGS, do not hesitate to speak to your kidney or nurse specialist at your kidney unit.
- Visit the Infokid website
- Visit Nephrotic Syndrome Trust
- Visit the National Kidney Federation website
Reviewed June 2025
"By looking more closely at the kidney and its patterns of injury, we hope to better understand the factors that lead to the disorder.”
Dr Katherine Bull
Researcher spotlight
In the last few years, a lot of progress has been made identifying the genetic mutations that cause inherited FSGS.
We now need to work on understanding how to prevent these mutations from damaging the kidney. Further research is needed on the causes of primary FSGS so that better treatments, with few side effects, can be developed.
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