Understanding FSGS: A Primary Cause of Kidney Disease

What is Focal Segmental Glomerulosclerosis (FSGS)?

Focal Segmental Glomerulosclerosis (FSGS) is a serious, rare scarring disease of the kidney’s filtering units. It is a leading cause of kidney failure worldwide. Today, approximately 20,000 people in the U.S. are living with end-stage kidney disease (ESKD) specifically due to FSGS.

FSGS generally leads to excess protein in the urine, a condition called nephrotic syndrome, and progressive loss of kidney function. Understanding the condition and its stages is crucial for managing chronic kidney disease (CKD).

There are four types of FSGS:²

The cause of FSGS determines its type, which guides treatment. The main types include:

Primary FSGS: The disease occurs spontaneously without an identifiable cause.
Secondary FSGS: This type is caused by another underlying health issue, such as infections, drug toxicity, diabetes, obesity, sickle cell disease, or other kidney diseases. Treating the underlying condition may slow or stop kidney damage.
Genetic (Familial) FSGS: A rare form caused by genetic mutations. This is suspected when multiple family members show signs of FSGS. Genetic FSGS can also occur if both parents carry an abnormal gene, even if neither has the disease.
Unknown FSGS: Despite extensive testing and evaluation of clinical symptoms, the specific underlying cause cannot be determined.

What is Nephrotic Syndrome?

Nephrotic syndrome is a collection of symptoms that signal your kidneys are not working properly. These symptoms include:

Proteinuria: Too much protein in the urine, often causing foamy urine.

Hypoalbuminemia: Abnormally low levels of the protein albumin in the blood.

Edema: Swelling, typically in the legs, ankles, and around the eyes.

Hyperlipidemia: High levels of cholesterol in the blood.

How Your Kidneys Are Affected

Your kidneys are composed of millions of filtering units called nephrons. Each nephron contains a glomerulus, which is a filter, and a tubule. The glomerulus filters your blood. Nephrotic Syndrome results when the glomeruli become inflamed or damaged, allowing protein that should remain in your body to leak into the urine instead. FSGS is estimated to be responsible for 40% of adult and 20% of pediatric nephrotic syndromes.

Signs, Symptoms, and Prevalence of FSGS

Early stages of FSGS may not cause any noticeable symptoms. Signs may be found during routine check-ups. Common symptoms of FSGS include:

Swelling (edema) in body parts like your legs, ankles, and around your eyes.
Weight gain due to extra fluid buildup in the body.
Foamy urine caused by high protein levels (proteinuria).
High cholesterol levels.
Low protein levels in the blood.

Please consult with your healthcare provider immediately if you exhibit any of these signs and symptoms for a proper diagnosis.

Key FSGS Statistics

FSGS is currently the most common primary glomerular disease causing kidney failure in the U.S. and a major global cause of kidney disease.

More than 5,400 FSGS patients are diagnosed in the U.S. annually.¹

In adults, FSGS is more common
in men, with an approximate
1.5-fold increased incidence
compared to women.⁴

The incidence of FSGS is
around 4 times higher in
black patients compared
to white patients.⁵

Both adults and children are affected by FSGS, but it is most common in people over 45 years old. It occurs more often in men than in women and in African Americans than other ethnicities.

FSGS is estimated to be responsible for 40% of adult nephrotic syndromes and 20% of pediatric nephrotic syndromes.³

Diagnosis and Comprehensive Treatment of FSGS

Diagnosis of FSGS begins with several tests that check for protein, fat, and kidney function. These include blood tests, urine tests, and measuring Glomerular Filtration Rate (GFR). However, a definitive diagnosis can only be made with a kidney biopsy, where a small tissue sample is studied under a microscope. Doctors may also use genetic testing to confirm a diagnosis of genetic FSGS.

Treatment for FSGS is personalized based on the type, cause, patient age, and overall health. The goal of management is to control symptoms, slow progressive scarring, and prevent the development of ESKD.

Management and Treatment of FSGS

Treatment for FSGS depends on the type and cause, your age, and whether you have other health conditions. Doctors aim to control symptoms to help you maintain a good quality of life and slow or prevent progressive scarring so that it does not lead to kidney failure.

In some people with secondary FSGS, treating the underlying condition may stop kidney damage from progressing. Doctors cannot repair glomeruli, but over time, kidney function may improve in these people.

Treatments for FSGS may include:^1,6

Angiotensin-converting enzyme (ACE) inhibitors: Drugs that treat high blood pressure.
Antibiotics
Diuretics: Medications that lower blood pressure and ridding the body of excess fluids.
Immunosuppressive drugs: Drugs that manage the immune system response, such as cyclosporine and tacrolimus.
Corticosteroids (e.g. Prednisone): Drugs that lowers levels of protein in the urine.
Plasma Apheresis
Lipoprotein Apheresis

Frequently Asked Questions About FSGS

What is the role of ACE inhibitors in FSGS? ACE inhibitors are a cornerstone of FSGS treatment. They primarily reduce high blood pressure, but they also help reduce the amount of protein leaking into the urine (proteinuria), which protects the kidneys from further damage.

When are immunosuppressive drugs prescribed? Immunosuppressive drugs are typically reserved for Primary FSGS or severe cases. They work by lowering the activity of the immune system, which is believed to be attacking the kidney filters (glomeruli) in these forms of the disease.
Does FSGS always lead to kidney failure? Not always. With early diagnosis and aggressive management—including controlling blood pressure, using corticosteroids and other appropriate treatments—the progression to ESKD can often be significantly slowed, or in some cases, even stabilized.

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