Nephrotic syndrome (excess proteinuria): Causes, symptoms, treatment, and diet

nephortic syndromeA nephrotic syndrome definition is a kidney disorder that results in the release of too much protein in the urine (proteinuria). When damage is caused to the blood vessels within the kidneys, which filter waste and water, it can lead to nephrotic syndrome. Nephrotic syndrome leads to swelling of the feet and ankles along with other health conditions.

To treat nephrotic syndrome in adults and children, it’s important to treat the underlying health issue that is causing it. Because nephrotic syndrome can lead to other complications, it’s important to begin treatment right away.

Nephrotic syndrome causes and symptoms


Damage to the blood vessels, which filter water and waste, is one of the causes of nephrotic syndrome. When these vessels are healthy, they keep the appropriate amount of protein in the body and expel what’s extraneous. When they are damaged, too much protein leaves the body through the urine.

Other nephrotic syndrome causes include:

Minimal change disease: The most common cause of nephrotic syndrome in children, resulting in abnormal kidney function. Kidney tissue under the microscope appears normal despite the presenting symptoms of the condition.

Focal segmental glomerulosclerosis: Results in scattered scarring of the part of the kidney system called the glomeruli. This condition may be the result of another disease, a genetic defect, or an unknown cause.

Membranous nephropathy: Its exact cause is not known, but this disorder results in the thickening of membranes within the glomeruli. However, it may be associated with other medical conditions such as hepatitis B, malaria, lupus, and cancer.

Diabetic kidney disease: Long-term diabetes can lead to kidney damage, particularly when the condition is poorly controlled. This is termed diabetic nephropathy.

Systemic lupus erythematosus: A chronic inflammatory condition that can lead to serious kidney damage over time.

Amyloidosis: A result of the accumulation of amyloid proteins in your organs. When amyloidosis occurs, it can damage your kidney’s ability to filter blood.

Blood clot in a kidney vein: Blockage of a vein connected to the kidney can lead to nephrotic syndrome.

Heart failure: Nephrotic syndrome may occur as a result of certain forms of heart failure, such as constrictive pericarditis and severe right heart failure.

Symptoms of nephrotic syndrome include:

  • Swelling around the eyes, feet, and ankles
  • Foamy urine, which indicates protein
  • Weight gain due to fluid retention

Nephrotic syndrome risk factors and complications

The factors that increase your risk of developing nephrotic syndrome include kidney damage due to medical conditions like diabetes or lupus, use of medications like nonsteroidal anti-inflammatory drugs, and infections like HIV, hepatitis B and C, and malaria.

The complications of nephrotic syndrome include blood clots, high cholesterol, poor nutrition, chronic kidney disease, and an increased risk of infections.

Additional complications include:

Hypothyroidism: Where the thyroid gland does not produce sufficient thyroid hormone to regulate bodily processes.

Anemia: A condition where there are fewer or smaller red blood cells than normal. Red blood cells carry oxygen to be used by tissues and organs, including the kidney. If they are unable to complete this task, cell damage is likely to occur.

Coronary artery disease: Occurs due to the narrowing of the blood vessels of the heart and can lead to kidney problems from decreased perfusion of blood.

High blood pressure: A condition where blood flows with greater force than normal. This increased force can be particularly hard on the kidneys.

Acute kidney injury: Sudden or temporary loss of kidney function may lead to nephrotic syndrome.

Diagnosing nephrotic syndrome

There are three main ways to come to a diagnosis of nephrotic syndrome: a urine test, blood test, and kidney biopsy. A urine test will reveal abnormalities found in the urine, including protein. A blood test will reveal low levels of protein and high levels of cholesterol. A kidney biopsy will take a small tissue sample from the kidney and test it.

A lab-tested urinalysis can provide important information about the contents of the urine, such as high levels of protein. A urine dipstick test can be done in office, giving your doctor an instant idea of your kidney’s condition. A urine dipstick is simply a chemically treated paper strip that changes color according to certain concentrations in the urine.

The most accurate diagnostic test for nephrotic syndrome is a 24-hour urine sample test. However, it is seldom done as it involves collecting all of the patient’s urine in a 24-hour period, which is then sent to the lab for analysis. Most of the time, the ratio of albumin to creatinine is estimated from a single urine sample, in lieu of the more accurate 24-hour urine sample test.

Nephrotic syndrome treatment

Treatment involves gauging nephrotic syndrome symptoms and treating the underlying condition. Therefore, nephrotic syndrome treatment may include:

Taking blood pressure medication: The goal is to keep blood pressure at or below 130/80 mmHg to delay kidney damage. The most commonly used hypertensive medications known for having a protective effect on the kidneys are angiotensin-converting enzyme (ACE) inhibitors.

Water pills: Diuretics help to decrease blood pressure. They also help to control swelling by increasing urine output. Commonly used water pills include furosemide (Lasix) and spironolactone (Aldactone).

Cholesterol-reducing medications: While it is currently not clear whether cholesterol-lowering medication can improve the outcomes of those suffering from nephrotic syndrome, having controlled cholesterol levels does benefit overall health. A common class of these medications is called statins.

Blood thinners: Also known as anticoagulant medication, these drugs help to reduce the risk of blood clot formation.

Immune-system-suppressing medications: These help to control the inflammation that accompanies certain kidney disorders such as minimal change disease.

Nephrotic syndrome diet

It’s important to change your diet if you have nephrotic syndrome because unhealthy foods can further damage the kidneys. For starters, choose leaner sources of animal protein or even plant-based protein, which aren’t as taxing on the kidneys. You will also want to reduce the amount of fat and cholesterol in your diet to control cholesterol levels and reduce your risk of heart disease, which can worsen nephrotic syndrome. Lastly, reduce your salt intake to minimize swelling.

Knowing which foods to eat and which to avoid can assist with overall treatment of the condition. Since nephrotic syndrome results in high amounts of protein in the urine, swelling, decreased albumin levels, and abnormally high levels of fats or lipids in the blood, a healthy diet that takes these symptoms into account can help to protect the kidneys.

Generally, a diet for nephrotic syndrome that is low in salt, fat, and cholesterol is the way to go. Eating more fruits and vegetables is also recommended.

Foods considered natural diuretics that help to reduce swelling include white gourd, watermelon, mung bean, tomato, Laminaria japonica, agaric, celery, and many other fruits and vegetables.


Eating high-quality protein in low to moderate amounts is recommended. Good protein sources include egg whites, fish, and milk.

Supplementing with calcium and vitamin C may be required due to the effects of nephrotic syndrome.

Lastly, it is recommended that you avoid foods high in salt and protein, excess water, spicy food, coffee, and alcohol. It is advised to follow the instructions laid out by your doctor as additional nutritional advice for a nephrotic syndrome diet may be patient specific.

Author Bio

Emily Lunardo studied medical sociology at York University with a strong focus on the social determinants of health and mental illness. She is a registered Zumba instructor, as well as a Canfit Pro trainer, who teaches fitness classes on a weekly basis. Emily practices healthy habits in her own life as well as helps others with their own personal health goals. Emily joined Bel Marra Health as a health writer in 2013.


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