Focal segmental glomerulosclerosis (FSGS)
Focal segmental glomerulosclerosis (FSGS) is a rare type of kidney disease that causes scarring in some parts of the kidney filters, known as glomeruli. FSGS can make it hard for your kidneys to filter waste, which can lead to kidney failure, also called end-stage renal disease (ESRD) or end-stage kidney disease (ESKD).
- Medically reviewed by
- AKF's Medical Advisory Committee
- Last updated
- March 19, 2025
What is focal segmental glomerulosclerosis (FSGS)?
FSGS is a rare type of glomerular disease that causes scarring (sclerosis) in your kidneys. Glomerular diseases affect how well your kidneys work by attacking the tiny filters (called glomeruli) in your kidneys that clean your blood. In FSGS, only certain areas of these filters are affected, which makes it harder for your kidneys to function properly which can lead to decline in kidney function and progression to failure.
What are the symptoms of FSGS?
In early stages of FSGS, you may not notice any symptoms. As FSGS gets worse, you may start to notice symptoms like swelling in your legs or weight gain. Other symptoms will only be found by your doctor through tests, such as:
- Protein in your urine (pee), called proteinuria
- Low levels of protein in your blood
- Too much fat in your blood (high cholesterol)
Having one or more of these symptoms does not mean you have FSGS. If you start to notice one or more of these symptoms, talk to your doctor.
FSGS can lead to nephrotic syndrome. Nephrotic syndrome is a group of symptoms that may happen together, which can mean that your kidneys are not working as well as they should. Signs and symptoms of nephrotic syndrome include:
- Severe swelling around eyes and in your ankles and feet
- Foamy urine from protein in the urine
- Weight gain from fluid retention
- Fatigue
Will I have kidney failure because of FSGS?
FSGS is a long-term (chronic) condition that cannot be reversed. Scarring can make it hard for your kidneys to filter out waste from your body. While treatments can help slow its progress, some people with FSGS eventually develop kidney failure. If this happens, you will need a kidney transplant or dialysis to live.
What causes FSGS?
FSGS is rare. Doctors diagnose about 7 in every 1 million people per year. The exact causes of FSGS can vary.
What are the different types of FSGS?
FSGS is split into different types based on the cause. The three types of FSGS are:
- Primary FSGS: This type happens without a known or obvious cause. It is often linked to an abnormal response from the immune system or an unidentified factor in the blood that damages the kidney filters, but the exact cause of this factor is not always clear. People with primary FSGS may experience high protein levels in their urine, low protein levels in their blood, high cholesterol, swelling, and sometimes high blood pressure.
- Secondary FSGS: This type develops because of another condition or the use of certain medicines. For example, it can be triggered by problems with:
- How the kidneys are formed at birth
- Some medicines
- Viral infections like HIV, Parvovirus B19, or COVID-19
With secondary FSGS, kidney function may get worse over time, and protein levels in the urine can increase.
- Genetic (also called familial) FSGS: This type is passed down through your family (inherited). If any of your family members have FSGS or show symptoms of it, your FSGS might be genetic. Genetic FSGS can appear early in life with more severe symptoms or show up later with milder symptoms. Genetic testing can help identify this type.
- Undetermined FSGS: Sometimes, even after many tests, the exact cause of FSGS may remain unclear.
How will I know if I have FSGS?
To confirm if you have FSGS, your doctor will need to do a kidney biopsy. A kidney biopsy is a procedure where your doctors use a needle to take a small piece of your kidneys to look at it closely under a microscope.
Your doctor may also do other tests, including:
- Blood tests: To help find out how well your kidneys still work
- Urine tests: To check for blood and protein in your urine or other signs of problems
- Genetic testing: To see if you were born with a change (or mutation) in your DNA that caused your kidney disease
Information from these tests will help your doctor decide which treatment is best for you.
How do doctors treat FSGS?
The type of treatment plan your doctor will choose depends on what caused your FSGS. The goal of treatment is to stop proteinuria, the leaking of protein into your urine. For primary FSGS, treatment usually includes:
Medicines called immunosuppressants that will stop your body from attacking your kidneys. This can include glucocorticoids (often called "steroids") or another type of medicine called calcineurin inhibitors.
For secondary FSGS, treatment involves managing the condition that caused FSGS. This can include stopping a certain medicine or treating the viral infection.
- For all forms of FSGS, doctors recommend: Blood pressure medicines to lower the amount of protein lost and to control your blood pressure .
- Medicines called diuretics (water pills) that help your kidneys get rid of salt and water and make you urinate more to help reduce swelling in the body.
- Healthy life changes, such as following a kidney-friendly eating plan, being active for 30 minutes most days of the week and quitting smoking or other kinds of tobacco.
Plasma exchange
In some cases of FSGS especially when FSGS is recurrent, and after a kidney transplant, plasmapheresis (also known as plasma exchange or "PLEX") is a treatment option. This is a procedure where a plasmapheresis machine separates plasma (the liquid part of the blood) from the blood cells and it may involve placing a central venous catheter, or "central line" which is when a thin flexible tube that is placed in a vein to draw blood.
During this procedure, blood is taken from the body, and sent through the machine that separates the plasma from the rest of the blood. The old plasma is removed (which may contain harmful substances), and it is then replaced with plasma from a donor (which includes helpful substances like albumin and other fluids). The treated blood, with the new plasma is then returned to the body. This procedure has shown to help decrease protein loss in the urine (proteinuria) and may also help to improve response to other FSGS treatments. Some people may have several treatments over a few weeks depending on the response to the treatments.
Plasma exchange is a safe procedure but may have some side effects during or after the procedure that include low calcium levels, low body temperature, and low blood pressure. You will be monitored during the procedure to treat the side effects.
Your treatment plan will be unique to you and your condition. Talk with your doctor about other medicines and your options to help treat FSGS.
