Nephrotic syndrome
Nephrotic legs (normal for elephants), normal gazelle legs (Beth Shortt) illustrating oedema
Usually defined as proteinuria >3.5g/day with hypoalbuminaemia and oedema. Some definitions vary a little around exact values. Serum albumin levels are low because of the urinary protein loss. This leads to avid sodium and fluid retention by the kidneys, seen symptomatically as oedema.
Causes
These are mostly conditions in which there is podocyte (glomerular epithelial cell) damage or non-inflammatory architectural alterations of the glomerulus, such as that caused by matrix expansion associated with diabetes, or by scarring. Subacute inflammatory (nephritic) types of glomerulonephritis may cause nephrotic syndrome through causing scarring in the glomerulus. Most important causes of nephrotic syndrome:
| Minimal change disease | Normal glomeruli on light microscopy. Especially in children. Responds to treatment with high dose steroids. Does not cause renal failure. |
| Focal segmental glomerular sclerosis (FSGS) | Focal scars in glomeruli. Variable response to steroids. May progress to renal failure. |
| Membranous nephropathy | Usually idiopathic (autoimmune); sometimes due to drugs, rarely malignancy. May progress to renal failure in up to 30%; immunosuppression may halt progression if function deteriorating. |
| Diabetes mellitus | After long history of diabetes and with other microvascular complications. |
| Amyloidosis | Most types cause renal disease (usually nephrotic syndrome) as an early manifestation. |
| Systemic lupus erythematosus (SLE) | Young women usually. May present in many ways but sometimes as renal disease alone. |
Complications
- Susceptibility to infection
- Increased risk of venous thrombosis
- High cholesterol – often extreme (>10 mmol/L)
Investigation
Renal biopsy often required unless obvious (e.g. long history of diabetes with other complications and typical evolution and features). Minimal change disease usually assumed in children, unless fails to respond to steroids.
Management
- Diet - control salt intake
- Loop diuretics - to control salt and water retention
- ACE inhibitors - to control blood pressure, reduce proteinuria
- Anticoagulation - if immobilised, or thrombosis has occurred
- Lipid lowering - consider statin if syndrome persistent
Further info
- Patient info on Nephrotic syndrome
- Tutorial on glomerulonephritis
- Edren handbook on Nephrotic syndrome
Wordle
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