This information from Great Ormond Street Hospital (GOSH) is about Focal segmental glomerulosclerosis (FSGS). FSGS is not one but many different diseases.
How does the urinary system work?
The urinary system consists of the kidneys, ureters, the bladder and urethra. The kidneys filter the blood to remove waste products and produce urine. The urine flows from the kidneys down through the ureters to the bladder, where it is stored until we go to the toilet. It passes through another tube called the urethra to the outside when urinating (peeing).
The kidneys contain millions of tiny filtering units called glomeruli. As blood passes through the tubes in the glomerulus, waste products pass through the walls of the tubes to form urine. Blood cells and other things such as protein cannot pass through the walls because they are too big.
When someone has focal segmental glomerulosclerosis (FSGS), some of the glomeruli are damaged and become scarred. This stops them working properly, so that protein can pass through the walls of the glomerulus and into the urine. This means that the child develops nephrotic syndrome.
What are the symptoms of FSGS?
The main symptom of FSGS is the development of nephrotic syndrome, that is, swelling due to increased fluid in the body. Nephrotic syndrome occurs because the kidneys leak protein. This results in low protein levels in the blood, which means that fluid is shifted out of vessels into tissues. This causes puffiness, particularly around the eyes, abdomen, feet and legs, and weight gain. The medical word for this puffiness is oedema. As the kidney leaks protein, the urine’s appearance changes so that it appears foamy, which is a sign of proteinuria.
How is FSGS diagnosed?
The doctor will ask lots of questions about how the child became ill and examine them. Various tests will be needed to confirm or rule out FSGS:
- Urine tests to see how much protein is present in the urine.
- Blood tests to check general health, and possibly genetic tests, which we will discuss with the family.
- Kidney biopsy to see if any areas contain scarring.
Other tests may also be needed if the results of these tests are not completely clear.
What causes FSGS?
There are many different kinds of FSGS. Some are caused by inherited diseases and can thus affect several members of the family. In other cases the cause is unknown and it might be caused by an autoimmune reaction, where the body starts to attack itself after mistakenly recognising itself as the ‘enemy’.
How common is FSGS?
We do not yet know exactly how many children each year are affected by FSGS but at GOSH, we have looked after at least 66 children with this condition over the last 15 years.
Reports vary but it would seem that between seven and 10 per cent of kidney biopsies to investigate proteinuria lead to a diagnosis of FSGS. It seems to be more common in certain racial groups but again we do not yet know why.
How is FSGS treated?
Normally the first sign of FSGS is nephrotic syndrome, where protein is continuously lost in the urine. The child will start with the standard treatment for nephrotic syndrome, which is steroid medicine.
Many cases of FSGS do not respond to steroids, so are called 'steroid resistant'. In those cases, we try immunosuppressive medicines that damp down the immune system. Unfortunately a large proportion of FSGS does not respond to this kind of medicines.
Whether the child is taking steroids or immunosuppressive medicines, families may need to postpone some of their child’s immunisations while taking the medicines. It should also be reported to the family doctor (GP) if a child comes into contact with chicken pox unless he or she has already had it. Other precautions are included in our medicines information sheets.
We also use a group of medicines called ACE (angiotensin converting enzyme) inhibitors and ARBs (angiotensin receptor blockers) to reduce the protein loss and blood pressure. Diuretics (water tablets) are also prescribed to reduce the puffiness.
It is important that the amount of protein lost in the child’s urine is monitored closely. We may ask families to do these measurements every day at home, using a dipstick. We would explain how to do this. These measurements will need to be recorded alongside details of the child’s steroid dose and any other medicines for each day, which should be brought to each clinic appointment, as they are a good indicator of how treatment is working.
Diet also plays a part in treating FSGS. We may suggest reducing the amount of salt used at home. Our dietitian will explain exactly what needs to be done and will be available for advice afterwards.
What is the outlook for children with FSGS?
FSGS is a chronic condition. An infant's health may improve for a while, but many children do not respond very well to the treatment. In others who respond the symptoms might come back. If this happens, he or she will have to start taking the steroid or immunosuppressive medicines again.
Over time, more areas of the glomeruli become scarred, which affects the child’s overall kidney function. FSGS may eventually progress to irreversible kidney failure, although this could take many years.
In our experience of caring for children with FSGS at GOSH, three in 100 children died and a quarter of patients had irreversible kidney failure requiring kidney transplantation having been followed up for 10 years.
Once a child’s kidney function has dropped to a level where it is affecting his or her daily life, we would discuss dialysis and transplantation. This is called renal replacement therapy (RRT) and aims to keep children well until a transplant is possible. There is unfortunately a risk that the disease will come back in the transplanted kidney.
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