FSGS can develop as an isolated kidney disease (referred to as primary FSGS). In these cases, the cause of the disease is unknown. FSGS can also be due to other causes (referred to as secondary FSGS). In some of these cases, the disease may due to being born with too few glomeruli (ie. being born with a single kidney) or it may be associated with conditions that overwork the filters of the kidney such as with massive obesity. However, a wide variety of factors including infections, medications/toxins, chronic systemic diseases and other chronic kidney diseases can also result in the same pattern of disease. Rarely, the disease is inherited and much research is ongoing at the Glomerular Center at Columbia to understand the genes that may be responsible for the disease.
Primary FSGS affects individuals of all ages. It is an important cause of kidney problems in children. In adults, it is also increasingly seen. It occurs more frequently in black individuals compared to whites and is more frequent in males.
Symptoms:
Some people with FSGS develop swelling (edema) of the eyelids in the morning and edema of the legs and body late in the day due to retention of fluid and this is what leads them to seek medical attention. Some notice foamy or bubbly urine when they urinate (due to the protein in the urine). Because symptoms may develop gradually, the disorder may first be discovered when there is an abnormal urine test (with protein and blood) or blood test (abnormal kidney function) done for a routine physical exam or on exam for an unrelated disorder. Many patients will have high blood pressure at the time of diagnosis.
Diagnosis :
A kidney biopsy is necessary to establish the diagnosis of FSGS and to distinguish it from other diseases that may also cause protein loss in the urine and abnormal kidney function. In addition, the biopsy can help to distinguish the different types of FSGS and may provide important information about prognosis. Treatment can also be guided by the results of the biopsy.
Treatment:
Some treatment is used to control the symptoms associated with the disease as well as slow down the progression of the disease. Diuretics (“water pills”) are used to help rid the body of excess salt which causes the swelling (edema). Other medications are used to help control the blood pressure, particularly a group of drugs called angiotensin converting enzyme inhibitors (ACE inhibitors) and angiotensin receptor blockers (ARB). These same medications can help decrease the amount of protein that is lost by the kidney. Other drugs are often used to help reduce high blood cholesterol. In most cases, a moderate protein diet is usually recommended.
More specific treatment may be used to help alter the immune system and try to cure the disease. There are several treatments available. Steroids are often used initially for several months and up to 50% of individuals will improve with this medication. Other immunosuppression drugs may be used in addition to or instead of the steroids. These include a transplant medication, cyclosporine (and a related medication called tacrolimus) and a chemotherapy agent, cyclophosphamide. Some have recently tried a different type of immunosuppressant called mycophenolate mofetil (MMF). Each of these treatments have different side effects associated with them which should be discussed with the nephrologist. All can increase the risk of infections and this too must be discussed with the physicians caring for FSGS patients. .
In cases of FSGS that is secondary to other disorders, a major focus of therapy is treatment of the underlying disorder (such as weight loss or treatment of infections or other illness).
Prognosis:
The natural history of FSGS varies a great deal. Treatment may cure the disease (remission) in some or at least slow down the progression of the disease. Some individuals may initially respond to therapy but the disease may come back (relapse). Others will continue to slowly lose kidney function over years and may need to be on dialysis or require a kidney transplant.