Focal segmental glomerulosclerosis (FSGS)

Focal segmental glomerulosclerosis (FSGS) is a rare type of kidney disease that causes scarring in the filters of the kidneys. 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
December 15, 2023

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 in your kidneys that clean your blood (called glomeruli). In FSGS, "focal" means that only some filters in the kidney are scarred. "Segmental" means that in the filters that are affected, scars are only found on some parts (or segments) of the filters. 

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 (i.e, your pee)
  • 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. 

kidney dysfunction

Will I have kidney failure because of FSGS?

FSGS is a long-term (chronic) disease that cannot be reversed. Scarring can make it hard for your kidneys to filter out wastes from your body. Treatment can help slow down kidney disease but over time some patients with FSGS do reach kidney failure. If you reach kidney failure, 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. FSGS does not have any one known cause but there are some health problems that are thought to cause FSGS, including:

  • Diabetes 
  • Sickle cell disease 
  • Infections, including some viruses like HIV
  • Lupus 
  • Being overweight
  • High blood pressure
  • Long-term use of some drugs such as heroin or drugs used to grow muscle (anabolic steroids)
  • Too much urine in your kidneys
  • Medicines, such as some cancer treatments
  • Problems with your kidneys since birth (a birth defect)

Having one or more of these conditions does not mean you will have FSGS. If you are worried about how any of these conditions may affect your kidneys, talk to your doctor. 


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: Happens without a known or easy-to-see cause
  • Secondary FSGS: Caused by another condition or drug use
  • Genetic (also called familial) FSGS: Passed down through your family (inherited). This could be the cause of your FSGS if any of your family members show symptoms of or have been diagnosed with FSGS. 

How will I know if I have FSGS?

To see if you have FSGS, your doctor will need to do a kidney biopsy. A kidney biopsy is a procedure where your doctors 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 problem that caused your kidney disease 

Information from these tests will help your doctor decide which treatment is best for you.