| Nephrotic syndrome | |
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| Classification and external resources | |
Histopathological image of diabetic glomerulosclerosis with nephrotic syndrome. H&E stain. |
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| ICD-10 | N04 |
| ICD-9 | 581.9 |
| DiseasesDB | 8905 |
| eMedicine | med/1612 ped/1564 |
| MeSH | D009404 |
Nephrotic syndrome is a nonspecific disorder in which the kidneys are damaged, causing them to leak large amounts of protein[1] (proteinuria at least 3.5 grams per day per 1.73m2 body surface area)[2] from the blood into the urine.
Kidneys affected by nephrotic syndrome have small pores in the podocytes, large enough to permit proteinuria (and subsequently hypoalbuminemia, because some of the protein albumin has gone from the blood to the urine) but not large enough to allow cells through (hence no hematuria). By contrast, in nephritic syndrome, RBCs pass through the pores, causing hematuria.
According to NephCure, most often, Nephrotic Syndrome is defined by its primary diseases that attack the kidney’s filtering system. Some of these cases are idiopathic.
Contents |
It is characterized by proteinuria (>3.5g/day), hypoalbuminemia, hyperlipidemia and edema which is generalized & also known as anasarca or dropsy. Common among 2–6 years old boys. The edema begins in the face. Lipiduria (lipids in urine) can also occur, but is not essential for the diagnosis of nephrotic syndrome. Hyponatremia also occurs with a low fractional sodium excretion.
Hyperlipidemia is caused by two factors:
A few other characteristics seen in nephrotic syndrome are:
Nephrotic syndrome has many causes and may either be the result of a disease limited to the kidney, called primary nephrotic syndrome, or a condition that affects the kidney and other parts of the body, called secondary nephrotic syndrome.
Primary causes of nephrotic syndrome are usually described by the histology, i.e. minimal change disease (MCD) like minimal change nephropathy which is the most common cause of nephrotic syndrome in children, focal segmental glomerulosclerosis (FSGS) and membranous nephropathy (MN) like membranous glomerulonephritis which is the main cause of nephrotic syndrome in adult.
They are considered to be "diagnoses of exclusion", i.e. they are diagnosed only after secondary causes have been excluded.
Secondary causes of nephrotic syndrome have the same histologic patterns as the primary causes, though may exhibit some differences suggesting a secondary cause, such as inclusion bodies.
They are usually described by the underlying cause.
Secondary causes by histologic pattern:
Membranous nephropathy (MN):
Focal segmental glomerulosclerosis (FSGS)[4]
Minimal change disease (MCD)[4]
Allergy
The gold standard in diagnosis of nephrotic syndrome is 24 hour urine protein measurement. Aiding in diagnosis are blood tests and sometimes imaging of the kidneys (for structure and presence of two kidneys), and/or a biopsy of the kidneys.
The following are baseline, essential investigations:
Urine sample shows proteinuria (>3.5 g per 1.73 m2 per 24 hours). It is also examined for urinary casts, which are more a feature of active nephritis.
High levels of cholesterol (hypercholesterolemia), specifically elevated LDL, usually with concomitantly elevated VLDL is typical.
Further investigations are indicated if the cause is not clear:
A broad classification of nephrotic syndrome based on underlying cause:
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Nephrotic syndrome |
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| Primary |
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Secondary | |||||||||||||||
Nephrotic syndrome is often classified histologically:
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Nephrotic syndrome |
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MCD |
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FSGS |
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MN |
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When someone presents with generalized edema, the following causes should be excluded:
Treatment includes:
Prophylactic anticoagulation may be appropriate in some circumstances.[5]
Reduce sodium intake to 1000–2000 mg daily. Foods high in sodium include salt used in cooking and at the table, seasoning blends (garlic salt, Adobo, season salt, etc.) canned soups, canned vegetables containing salt, luncheon meats including turkey, ham, bologna, and salami, prepared foods, fast foods, soy sauce, ketchup, and salad dressings. On food labels, compare milligrams of sodium to calories per serving. Sodium should be less than or equal to calories per serving.
Eat a moderate amount of high protein animal food: 3-5 oz per meal (preferably lean cuts of meat, fish, and poultry)
Avoid saturated fats such as butter, cheese, fried foods, fatty cuts of red meat, egg yolks, and poultry skin. Increase unsaturated fat intake, including olive oil, canola oil, peanut butter, avocadoes, fish and nuts. Eat low-fat desserts.
Increase intake of fruits and vegetables. No potassium or phosphorus restriction necessary.
Monitor fluid intake, which includes all fluids and foods that are liquid at room temperature. Fluid management in nephrotic syndrome is tenuous, especially during an acute flare.
The prognosis depends on the cause of nephrotic syndrome. It is usually good in children, because minimal change disease responds very well to steroids and does not cause chronic renal failure. However other causes such as focal segmental glomerulosclerosis frequently lead to end stage renal disease. Factors associated with a poorer prognosis in these cases include level of proteinuria, blood pressure control and kidney function (GFR).
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