Nephrotic syndrome is a kidney disorder where the glomeruli become damaged, allowing an excessive excretion of proteins into the urine.
Nephrotic syndrome is a consequence of the inflammation of the membrane tissue in the glomeruli of the kidney. The inflammation alter the glomerular filtration, leading to an increased leakage of protein into the urine.
The glomeruli (a single one is called a glomerulus) are tiny blood vessels located inside the kidneys where the blood is filtered. In each kidney, there are around 800,000 to 1 million glomeruli. Glomeruli allow a certain amount of water and waste products to leave the blood through the urine. Normally, proteins are unable to pass through the glomerular filter. However, when the glomeruli are damaged, as seen in nephrotic syndrome, large amounts of proteins leave the blood circulation and pass to the urine.
Nephrotic syndrome leads to a high level of proteins in the urine and a low level of proteins in the bloodstream. Cholesterol in the blood is also high and as a result of the lack of proteins in the blood, edema (swelling) is present.
In children, the most common cause is minimal change disease or MCD (80% of cases in children). In adults, membranous glomerulonephritis (membranous nephropathy) is the most common cause (30-40% of cases in adults).
Other kidney disorders that may cause nephrotic syndrome include:
Secondary causes of nephrotic syndrome include:
People who suffer from nephrotic syndrome are from all age groups, but it is more common in children between the ages of 18 months and 4 years.
People who suffer from nephrotic syndrome are from all age groups, but it is more common in children between the ages of 18 months and 4 years.
In children, boys are more frequently affected than girls are; in adults, the ratio male to female is closer to equal.
The main symptoms of nephrotic syndrome are:
Nephrotic syndrome is specifically defined by the presence of:
On a physical exam, edema (swelling) is usually present. Edema is the accumulation of fluid in the interstitial compartment of tissues within the body and it is a sign of the dilution of the interstitial protein concentration.
The urinalysis will reveal significant quantities of protein (more than 3.5 grams per day), and the presence of hyaline casts.
The blood test will reveal hypoalbuminemia (low albumin level <3 g/dl). Cholesterol (LDL cholesterol) and triglycerides will also be increased.
As a result of the previous tests, nephrotic syndrome can be diagnosed. To find the underlying cause there are several screening tests available:
To avoid a progressive deterioration of renal function is necessary to know the underlying cause in order to apply the proper treatment. Treating the underlying condition will often improve the symptoms of nephrotic syndrome as well.
The following drugs may be administered depending on the underlying cause:
Treatment with medication to lower cholesterol and triglyceride levels are often associated.
Anticoagulants may be prescribed if there is a risk of clot formation.
In addition, a moderate-protein diet (1 g of protein per kilogram per day) is recommended.
Salt (sodium) should be restricted to reduce inflammation and edema.
Vitamin D intake is recommended when the nephrotic syndrome is chronic and does not respond to the treatment.
Nephrotic syndrome can be acute and transitory as a consequence of, for example, an infection. In other cases, nephrotic syndrome may be chronic and lifelong treatment will be required.
When the kidney disorder is caused by the minimal change disease, the prognosis is very favorable with more than 90% of all patients responding to treatment. When nephrotic syndrome is caused by an infection, an allergic reaction, or a drug-induced reaction, the prognosis is also favorable.
The main complications related to nephrotic syndrome are:
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