Nephrotic syndrome is a nonspecific disorder in which the kidneys are damaged, causing them to leak large amounts of protein (proteinuria at least 3.5 grams per day per 1.73m2 body surface area) from the blood into the urine.
Definition : Nephrotic syndrome is a group of symptoms including protein in the urine (more than 3.5 grams per day), low blood protein levels, high cholestrol levels, and swelling. The urine may also contain fat, which can be seen under the microscope.
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.
Causes, incidence, and risk factors :
Nephrotic syndrome is caused by various disorders that damage the kidneys, particularly the basement membrane of the glomerulus. This immediately causes abnormal excretion of protein in the urine.
The most common cause in children is minimal change Disease, while membranous glomerulonephritis is the most common cause in adults.
This condition can also occur as a result of infection, use of certain drugs,caner, genetic disorders, immue disorders, or diseases that affect multiple body systems including diabetes, multiple myeloma, and amyloidosis.
It can accompany kidney disorders such as glomerulonephritis, focal and segmental glomerulosclerosis, and mesangiocapillary glomerulonephritis.
Nephrotic syndrome can affect all age groups. In children, it is most common from age 2 to 6. This disorder occurs slightly more often in males than females.
It is characterized by proteinuria (>3.5g/day), hypoalbuminemia, hyperlipidemia and edema. A few other characteristics are:
common sign is excess fluid in the body. This may take several forms:
Puffiness around the eyes, characteristically in the morning.
Edema over the legs which is pitting (i.e., leaves a little pit when the fluid is pressed out, which resolves over a few seconds).
Fluid in the pleural cavity causing pleural effusion. More commonly associated with excess fluid is pulmonary edema.
Fluid in the peritoneal cavity causing ascites.
Some patients may notice foamy urine, due to a lowering of the surface tension by the severe proteinuria. Actual urinary complaints such as hematuria or oliguria are uncommon, and are seen commonly in nephritic syndrome.
May have features of the underlying cause, such as the rash associated with Systemic Lupus Erythematosus, or the neuropathy associated with diabetes.
Examination should also exclude other causes of gross edema-especially the cardiovascular and hepatic system.
The following are baseline, essential investigations
Urine sample shows proteinuria (>3.5 per 1.73 m2 per 24 hour). It is also examined for urinary casts; which is more a feature of active nephritis.
Comprehensive metabolic panel (CMP) shows Hypoalbuminemia: albumin level ?2.5g/dL (normal=3.5-5g/dL).
High levels of cholesterol (hypercholesterolemia), specifically elevated LDL, usually with concomitantly elevated VLDL
Electrolytes, urea and creatinine (EUCs): to evaluate renal function
Further investigations are indicated if the cause is not clear
Biopsy of kidney :
Auto-immune markers (ANA, ASOT, C3, cryoglobulins, serum electrophoresis)
Classification and causes :
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 :
Primary causes of nephrotic syndrome are usually described by the histology, i.e., minimal change disease (MCD), focal segmental glomerulosclerosis (FSGS) and membranous nephropathy (MN).
They are considered to be "diagnoses of exclusion", i.e., they are diagnosed only after secondary causes have been excluded.
Secondary causes :
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 :
Systemic lupus erythematosus (SLE)
Focal segmental glomerulosclerosis (FSGS)
Human immunodeficiency virus (HIV)
Minimal change disease (MCD)
Malignancy, especially Hodgkin's lymphoma
Differential diagnosis of gross edema:
When someone presents with generalized edema, the following causes should be excluded:
Heart failure: The patient is older, with a history of heart disease. Jugular venous pressure is elevated on examination, might hear heart murmurs. An echocardiogram is the gold standard investigation.
Liver failure: History suggestive of hepatitis/ cirrhosis: alcoholic, IV drug user, some hereditary causes.
Stigmata of liver disease are seen: jaundice (yellow skin and eyes), dilated veins over umbilicus (caput medusae), scratch marks (due to widespread itching, known as "pruritus"), enlarged spleen, spider angiomata, encephalopathy, bruising, nodular liver
Acute fluid overload in someone with kidney failure: These people are known to have kidney failure, and have either drunk too much or missed their dialysis.
Metastatic cancer: When cancer seeds the lungs or abdomen it causes effusions and fluid accumulation due to obstruction of lymphatics and veins as well as serous exudation. iagnosis
Diagnosis is based on blood and urine tests and sometimes imaging of the kidneys, a biopsy of the kidneys, or both.
General measures (supportive)
Monitoring and maintaining euvolemia (the correct amount of fluid in the body):
monitoring urine output, BP regularly
fluid restrict to 1L
diuretics (IV furosemide)
Monitoring kidney function:
do EUCs daily and calculating GFR
Prevent and treat any complications [see below]
Albumin infusions are generally not used because their effect lasts only transiently.
Prophylactic anticoagulation may be appropriate in some circumstances.
Specific treatment of underlying cause:
Immunosupression for the glomerulonephritides (corticosteroids, cyclosporin).
Standard ISKDC regime for first episode: prednisolone -60 mg/m2/day in 3 divided doses for 4 weeks followed by 40 mg/m2/day in a single dose on every alternate day for 4 weeks.
Relapses by prednisolone 2 mg/kg/day till urine becomes negative for protein. Then, 1.5 mg/kg/day for 4 weeks.
Frequent relapses treated by: cyclophosphamide or nitrogen mustard or cyclosporin or levamisole.
Achieving stricter blood glucose control if diabetic.
Blood pressure control. ACE inhibitors are the drug of choice. Independent of their blood pressure lowering effect, they have been shown to decrease protein loss. Dietary recommendations
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Reduce sodium intake to 1000-2000 milligrams 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. There is 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.
Venous thrombosis: due to leak of anti-thrombin 3, which helps prevent thrombosis. This often occurs in the renal veins. Treatment is with oral anticoagulants (not heparin as heparin acts via anti-thrombin 3 which is lost in the proteinuria so it will be ineffective.)
Infection: due to leakage of immunoglobulins, encapsulated bacteria such as Haemophilus influenzae and Streptococcus pneumonia can cause infection.
Acute renal failure is due to hypovolemia. Despite the excess of fluid in the tissues, there is less fluid in the vasculature. Decreased blood flow to the kidneys causes them to shutdown. Thus it is a tricky task to get rid of excess fluid in the body while maintaining circulatory euvolemia.
Pulmonary edema: again due to fluid leak, sometimes it leaks into lungs causing hypoxia and dyspnoea.
Growth retardation: does not occur in MCNS.It occurs in cases of relapses or resistance to therapy. Causes of growth retardation are protein deficiency from the loss of protein in urine, anorexia (reduced protein intake), and steroid therapy (catabolism).
Vitamin D deficiency can occur. Thyroxine is reduced due to decreased thyroid binding globulin.
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About the Author
Dr Harshad Raval MD[hom]
Honorary consultant homeopathy physician to his Excellency governors of Gujarat India. Qualified MD consultant homeopath ,International Homeopathy adviser, books writer and columnist. Specialist in kidney, cancer, psoriasis, leucoderma and other chronic disease,. www.homeopathyonline.in
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