Focal segmental glomerulosclerosis
| Focal segmental glomerulosclerosis | |
|---|---|
| Specialty | Nephrology  |
Focal segmental glomerulosclerosis (FSGS) is a cause of nephrotic syndrome in children and adolescents, as well as an important cause of kidney failure in adults. Minimal change disease (MCD) is by far the most common cause of nephrotic syndrome in children. MCD and primary FSGS may have a similar cause.
The individual components of the name refer to the appearance of the kidney tissue on biopsy: focal - only some of the glomeruli are involved (as opposed to diffuse), segmental - only part of an entire glomerulus is involved (as opposed to global), glomerulosclerosis - refers to scarring of the glomerulus (a part of the nephron (the functional unit of the kidney))
Symptoms & Signs
In children and some adults, FSGS presents as a nephrotic syndrome (which is characterized by edema (associated with weight gain), hypoalbuminemia (low albumin (a protein) in the blood), hyperlipidemia and hypertension (high blood pressure)). In adults it may also present as kidney failure and proteinuria, without a full-blown nephrotic syndrome.
Classification
Depending on the cause it is broadly classified as
- Primary, when no underlying cause is found; usually presents as nephrotic syndrome
- Secondary, when an underlying cause is identified; usually presents with kidney failure and proteinuria. This is actually a heterogeneous group including a myriad causes such as
- Infections such as HIV
- Toxins and drugs such as heroin and pamidronate
- Familial forms
- Secondary to nephron loss and hyperfiltration, such as with chronic pyelonephritis and reflux, morbid obesity, diabetes mellitus
There are many other classification schemes also.
Pathologic variants
Five mutually exclusive variants of focal segmental glomerulosclerosis may be distinguished by the pathologic findings seen on renal biopsy:[1]
- Collapsing variant
- Glomerular tip lesion variant
- Cellular variant
- Perihilar variant
- Not otherwise specified (NOS) variant.
Recognition of these variants may have prognostic value in individuals with primary focal segmental glomerulosclerosis (i.e. where no underlying cause is identified). The collapsing variant is associated with higher rate of progression to end-stage renal disease, whereas glomerular tip lesion variant has low rate of progression to end-stage renal disease in most patients.[1] Cellular variant shows similar clinical presentation to collapsing and glomerular tip variant but has intermediate outcomes between these two variants. However, because collapsing and glomerular tip variant show overlapping pathologic features with cellular variant, this intermediate difference in clinical outcomes may reflect sampling bias in cases of cellular focal segmental glomerulosclerosis (i.e. unsampled collapsing variant or glomerular tip variant). The prognostic significance of perihilar and NOS variants has not yet been determined. The NOS variant is the most common subtype.[1]
Diagnosis
- urinalysis
- blood tests - cholesterol
- kidney biopsy
Differential Diagnosis
- Minimal change disease, especially in children
- several others
Treatment
- salt restriction and diuretics (water pills), such as furosemide, for edema
- antihypertensives (especially ACEIs) - if the blood pressure is too high
- treat present hyperlipidemia (e.g. statins, fibrates)
- Corticosteroids, such as prednisone - based on the clinical judgment of physician (no broad consensus/guideline)
- Plasmapheresis - blood cleansing using a machine to remove the patient's plasma and replaccing it with donor plasma.
- None - sometimes none of the above works and the patient will required dialysis with possibly later transplantation of a new kidney.
References
External links
- Kidcomm An online resource for parents dealing with childhood kidney diseases (FSGS, Nephrotic Syndrome and others)
- FSGS Clinical Trial An NIH sponsored nation-wide Clinical Trial for patients suffering from FSGS