Focal segmental glomerular sclerosis (FSGS)
Focal segmental glomerular sclerosis (FSGS) is not a single disease, but a pattern of kidney damage. It is one of the most common causes of nephrotic syndrome, especially in children and adolescents. Nephrotic syndrome occurs when the body loses high amounts of protein into the urine, often resulting in swelling of the body; over time, progressive scarring of the kidneys can lead to kidney failure.
Focal segmental glomerular sclerosis can be explained as follows:
- It is identified by the scarring, or “sclerosis,” of the kidney.
- The kidneys' filtering system is made up of glomeruli that work something like a kitchen colander. The body pours blood into the kidneys, and as it circulates, the water-like part of the blood escapes and becomes urine. In FSGS, these damaged glomeruli are scarred, and when water is filtered out of the blood, protein leaks out into the urine as well. This whole process is referred to as glomerulosclerosis.
- Not every filter is damaged, so the word “focal” is used in the title.
- It is “segmental” because only parts of each filter may be scarred.
Symptoms
- Edema - noticeable swelling in parts of the body, often visible around the eyes, hands and feet
- Hypoalbuminemia - low level of water-soluble protein [albumin] in the blood
- Proteinuria - large amounts of protein in the urine
- Hypertension- high blood pressure
Causes
FSGS can be a result of an autoimmune disease, in which the body attacks itself without a cause, or the result of a pre-existing medical condition such as the following:
Who is at risk?
- FSGS is sometimes linked to a hereditary gene. Having a family member with FSGS may increase the chance of acquiring the disease. Most people do not know they have a genetic risk until they show the symptoms. Some of the genes known to be associated with FSGS are alpha actinin, WT1, and podocin.
- It is proportionally more common in African-Americans than other groups.
How FSGS is diagnosed
A urine test is taken and if protein is found, a kidney biopsy is done to see if there is kidney scarring. A biopsy revealing no scarring may lead to a different diagnosis called minimal-change disease, a kidney disease that is often effectively treated with steroids. It is important to return to the kidney doctor regularly to make sure the condition does not worsen.
Treatment
FSGS is a severe form of nephrotic syndrome, and while no cure currently exists, medical care can improve the patient's quality of life. It is important to try to reduce the amount of protein escaping from the kidneys.
- A low sodium diet and avoiding non-steroidal anti-inflammatory drugs can help protect the kidneys.
- Immunosuppressants and steroids may be prescribed. However, FSGS is associated with a steroid resistant gene, so most children with FSGS do not respond to any immunosuppressant therapy.
- Medication: ACE-inhibitors (angiotensin converting enzyme inhibitors) and ARBs (angiotensin receptor blockers)
- Within a few years of diagnosis, some patients may need to start dialysis.
- If the patient's condition continues to worsen, kidney failure can occur and a kidney transplant would be needed. Receiving a kidney from a relative is ideal. More here about kidney transplantation.
- Because of the similarities between the donated kidney and the patient, the kidney may last longer.
- In some patients with FSGS, the condition can recur after kidney transplantation, sometimes as soon as a few days.
- Plasmapheresis is a technique that may allow for the removal of the FSGS factor and results in slow disappearance of proteinuria after transplantation.
- Kidney transplantation from a live donor may not be recommended in this situation.
Life post-transplant
- Provided the transplant functions well, dialysis will no longer be required.
- In some patients, the kidney transplant may not function forever. Receiving a second kidney transplant may be an option.
- Transplant success rates are approximately 95% after 1 year, 80% after 5 years and 70% after 10 years.
More about FSGS
- Approximately 5,400 patients are diagnosed with FSGS every year.
- Roughly 26 million Americans suffer from chronic kidney disease, FSGS being one of the most common forms, according to NephCure, a foundation of doctors and researchers committed FSGS research.
- About 14.4% of dialysis patients are being treated for FSGS, with children as the most prevalent group.
- Approximately 15% of FSGS patients have a kidney transplant, but because of recurrent FSGS, may lose the kidney.
Ongoing research involving our hospital, Northwestern University and collaborators around the country is continuing toward the goal of effective treatment of the condition and its prevention.