Focal Segmental Glomerulosclerosis (FSGS)
FSGS is a rare disease that attacks the kidney’s filtering units (glomeruli) and causes serious scarring, leading to permanent kidney damage and even kidney failure. FSGS is one of the causes of a serious condition known as Nephrotic Syndrome.
Focal Segmental Glomerulosclerosis (FSGS) is a rare kidney disease characterized by dysfunction in the part of the kidney that filters blood (the glomeruli). Only some glomeruli are affected, but continued damage can lead to kidney failure.
Each kidney is made up of approximately one million tiny filters called “glomeruli.” Much like a coffee filter keeps coffee grounds in, glomeruli filter the blood, taking out the water-like part, which becomes urine, and leaving the protein in the blood. When glomeruli become damaged or scarred (sclerosis), proteins begin leaking into the urine (proteinuria). “Focal” refers to the fact that FSGS only leads to some of the glomeruli filters becoming scarred; “segmental” means that only some sections of those glomeruli become scarred.
With FSGS, many individuals experience cycles of remission and relapse. Many people with FSGS experience no symptoms at all. When symptoms are present, the most common include:
- Swelling in parts of the body, most noticeable around the eyes, hands, feet, and abdomen (edema)
- Weight gain due to extra fluid building up in the body
- High blood pressure (hypertension)
- High fat levels in the blood (high cholesterol)
- Protein in the urine, which can be foamy (proteinuria)
- Low levels of protein in the blood (hypoalbuminemia)
- High levels of creatinine in the blood due to your kidneys not filtering properly. Find out more about your lab values here.
To diagnose FSGS, doctors examine a tiny portion of the kidney tissue in a procedure called a biopsy. However, because FSGS only affects some sections of the glomeruli, biopsies can sometimes be inconclusive.
Other diagnostic tools may include:
- Urinalysis: determines the amount of protein in the urine
- Blood work: determines levels of creatinine, albumin, cholesterol, and many other factors examined to rule out other causes
- Glomerular filtration rate (GFR): Your GFR estimates your kidney function by calculating blood creatinine levels with urine protein levels. Click here for a GFR calculator.
- Ultrasound: sometimes performed to get a closer look at the kidneys
In the U.S., approximately 40,000 people are living with FSGS, and more than 5,400 people are diagnosed with FSGS every year. This is considered an underestimate, however, because a limited number of biopsies are performed, and the number of FSGS cases are rising more than any other cause of Nephrotic Syndrome.
FSGS is one of the leading causes of end-stage kidney disease (ESKD) in children, and is associated with up to 20% of all new cases of Nephrotic Syndrome in children each year.
FSGS occurs more frequently in adults than in children and is most prevalent in adults aged 45 and older. Black Americans are at least four times more likely to get FSGS in comparison with white Americans.
FSGS is not a single disease, but a pattern of glomerular injury. There are four main types of FSGS:
- Primary FSGS: FSGS with wide-spread damage to the kidneys' filters and accompanying nephrotic syndrome, often with a sudden onset. Primary FSGS means that the disease occurred on its own without a known or obvious reason. The exact cause of primary FSGS is unknown and not precisely understood.
- Genetic FSGS: FSGS with a known genetic cause. There are some known genetic causes of FSGS, and new gene variants are continually being discovered. Because of the genetic element, this type of FSGS tends to occur in families.
- APOL1 FSGS is a distinct form of genetic FSGS. It's caused by genetic variants in the APOL1 gene found only in individuals with recent African or Caribbean ancestry, and could explain why the rates of severe kidney disease are high in individuals of African and Caribbean descent.
- Secondary FSGS: FSGS caused by other diseases or conditions that occurred first, such as diabetes or hypertension. Other causes of secondary FSGS include:
- Kidney defects from birth (dysplasia)
- Urine backing up into kidneys (kidney reflux)
- Obstructive sleep apnea
- Viruses and blood disorders (such as HIV and sickle cell anemia)
- Autoimmune disorders (such as lupus and HSP)
- FSGS of undetermined cause (FSGS-UC): FSGS with dispersed damage to the kidneys' filters, no evidence of a secondary cause, and proteinuria without having nephrotic syndrome.
There are currently no FDA-approved medicines to treat FSGS. The standard first-line (initially prescribed) treatment for FSGS is prednisone, a corticosteroid aimed at decreasing proteinuria.
The short-term goal of treatment is to stop protein spillage completely (known as remission) or lower the amount of protein lost in the urine as much as possible. The less protein lost in the urine, the better the patient will do. With FSGS, even partial remission is important.
The long-term goals of treatment include preventing relapses of protein in the urine and preventing the deterioration of kidney function.
Your nephrologist may also recommend:
- Medications that suppress your immune system
- Diuretics and a low-salt diet to help control edema
- A medication that blocks a hormone system called the renin angiotensin system (ACE inhibitor or ARB) to control blood pressure or lower urine protein
- Anticoagulants to prevent blood clots
- Statins to lower the cholesterol level
- Maintaining a healthy diet and regulating protein and fluid intake according to your nephrologist's recommendations. A healthy diet consists of low-sodium foods with an emphasis on fruits and vegetables that are low in saturated fat and cholesterol.
- Not smoking
- Taking vitamins
1. Following a low-sodium diet may help your kidneys’ function and improve your FSGS symptoms.
2. Finding a nephrologist that specializes in FSGS that you trust is very important to your long-term health.
3. Learn about your disease, treatment options, and clinical trials in order to better advocate for yourself.
4. NephCure Kidney International can help you connect with other patients and find support to manage your disease.
In the U.S., approximately 40,000 patients are living with FSGS, and more than 60% of patients do not have a durable response to current FSGS treatments. Because of this, 50% of patients with FSGS will progress to kidney failure.
There are approximately 20,000 FSGS patients with end-stage kidney disease (ESKD), but only around 1,000 receive kidney transplants every year. Unfortunately, FSGS comes back to attack the new kidney 30-50% of the time.
There are currently no FDA-approved medicine treatments for FSGS — but right now, the future looks more promising than ever before. There are at least 20 potential new medicines for Nephrotic Syndrome diseases in various phases of clinical trials. These clinical trials are absolutely essential in making new treatments possible, and they need patient involvement to succeed.
That's why NephCure launched KidneyHealthGateway.com, an online platform that connects Nephrotic Syndrome patients with clinical trials in order to advance research and eventually find a cure for FSGS and other protein-spilling kidney diseases. Access breakthrough clinical trials, expert care, and one-on-one patient support all in one place — click here to visit KidneyHealthGateway.com and find the clinical trial right for you.
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This educational content is sponsored by Pfizer Inc.