Nephrotic syndrome – causes, symptoms, treatment. Nephrotic syndrome in children and adults

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Nephrotic syndrome occurs when damage to the kidneys causes the organs to release too much protein into the urine. Nephrotic syndrome is usually caused by damage to the clusters of small blood vessels in the kidneys that filter waste and excess water from the blood. This condition causes swelling, especially in the feet and ankles, and increases the risk of other health problems. Treatment for nephrotic syndrome includes treating the underlying condition and taking medications. Nephrotic syndrome can increase the risk of infections and blood clots. Nephrotic syndrome is not a disease in itself. Diseases that damage the blood vessels in the kidneys cause this syndrome.

What is nephrotic syndrome?

Nephrotic syndrome is a group of symptoms that indicate that the kidneys are not working properly. These symptoms include:

1. too much protein in the urine called proteinuria;
2. low levels of a protein called albumin in the blood called hypoalbuminaemia;
3. swelling of parts of the body (especially around the ankles and feet and around the eyes);
4. high levels of cholesterol and other lipids (fats) in the blood called hyperlipidaemia.

In addition to the symptoms above, people with nephrotic syndrome may also experience:

1. foamy urine;
2. weight gain due to fluid build-up in the body;
3. fatigue;
4. loss of appetite.

Our kidneys are made up of about a million filter units called nephrons. Each nephron contains a filter called a glomerulus and a channel. The clumps filter the blood and tubules return needed substances to the blood and remove waste and extra water that becomes urine. Nephrotic syndrome usually occurs when the glomeruli are inflamed, allowing too much protein from the blood to leak out into the urine.

See also: Protein in urine – causes, symptoms and treatment [EXPLAINED]

Nephrotic syndrome – causes

Nephrotic syndrome is usually caused by damage to the clusters of tiny blood vessels (glomeruli) in the kidneys.

Clumps filter the blood that passes through the kidneys, separating things the body needs from those it doesn’t. Healthy glomeruli trap a protein in the blood (mainly albumin) – which is needed to maintain adequate fluid in the body – from leaking into urine. Damaged glomeruli allow too much of the blood protein to leave the body, leading to nephrotic syndrome.

Many diseases and conditions can damage the glomeruli and lead to nephrotic syndrome. We can talk here about two groups of diseases and conditions:

Root causes of nephrotic syndrome

Some conditions causing nephrotic syndrome only affect the kidneys. These are the so-called primary causes of nephrotic syndrome. They include:

1. minimal change disease (MCD). It is the most common cause of nephrotic syndrome in children. The disease causes abnormal kidney function, but when the kidney tissue is examined under a microscope, it appears normal or nearly normal. The cause of the malfunction cannot usually be determined.
2. focal segmental glomerulosclerosis. Characterized by scarring of certain glomeruli, this condition may be due to another disease, genetic defect, or certain medications, or occurs for no known reason.
3. membranous nephropathy. This kidney disorder is the result of thickening of the membranes in the glomeruli. The thickening is caused by deposits made by the immune system. It can be associated with other conditions such as lupus, hepatitis B, malaria, and cancer, or it can occur for no known reason.
4. renal vein thrombosis. In this condition, a blood clot blocks the vein that drains blood from the kidney.

Secondary causes of nephrotic syndrome

Other diseases that cause nephrotic syndrome affect the entire body. These are the so-called secondary causes of nephrotic syndrome. Such diseases can include:

1. systemic lupus erythematosus. This chronic inflammatory disease can lead to severe kidney damage.
2. diabetic kidney disease. Diabetes can lead to damage to the kidneys (diabetic nephropathy) that affects the glomeruli.
3. amyloidosis. This disorder occurs when amyloid proteins build up in our organs. Amyloid accumulation often damages the kidney’s filtration system.

Certain medications, including drugs to fight infection and non-steroidal anti-inflammatory drugs (NSAIDs), are also associated with nephrotic syndrome.

See also: What do the kidneys do and what do kidney diseases manifest?

Nephrotic syndrome – risk factors

Anyone can get nephrotic syndrome, but it’s slightly more common in men than in women. In children, it most often happens between the ages of 2 and 6. There are other factors that can increase your risk.

Factors that may increase your risk of nephrotic syndrome include:

1. medical conditions that can damage the kidneys. Certain diseases and conditions increase the risk of developing nephrotic syndrome, such as diabetes, lupus, amyloidosis, reflux nephropathy, and other kidney diseases.
2. certain medications. Drugs that can cause nephrotic syndrome include non-steroidal anti-inflammatory drugs and drugs used to fight infection.
3. some infections. Infections that increase the risk of nephrotic syndrome include HIV, hepatitis B, hepatitis C, and malaria.

Nephrotic syndrome in children

Both primary and secondary nephrotic syndrome can occur in children. Primary nephrotic syndrome is the most common type of trusted source in children.

Some babies may have what is called congenital nephrotic syndrome, which starts in the first 3 months of life. This could be due to an inherited genetic defect or an infection shortly after birth. Children with this condition may eventually need a kidney transplant.

In children, nephrotic syndrome causes the following symptoms:

1. fever, fatigue, irritability and other signs of infection;
2. loss of appetite;
3. blood in urine;
4. diarrhea;
5. high blood pressure.

Children with childhood nephrotic syndrome have more infections than usual. This is because the proteins that would normally protect them from infection are lost in the urine. They may also have high blood cholesterol.

See also: Kidney Transplant Better Than Dialysis? Specialists about living kidney donation

Nephrotic syndrome in adults

As in children, nephrotic syndrome in adults can have primary and secondary causes. In adults, the most common primary cause of nephrotic syndrome is focal segmental glomerulosclerosis (FSGS).

This state is associated with a worse outlook. The amount of protein present in the urine is an important factor in determining the prognosis of these people. About half of people with FSGS and nephrotic syndrome progress to end-stage kidney disease within 5 to 10 years.

However, secondary causes of nephrotic syndrome also play an important role in adults. It is estimated that more than 50 percent of adult nephrotic syndrome cases have a secondary cause, such as diabetes or lupus.

Nephrotic syndrome – complications

Possible complications of nephrotic syndrome involve different systems.

1. Blood clots. The inability of the glomeruli to filter the blood properly can lead to a loss of blood proteins that help prevent clotting. This increases the risk of a blood clot in the veins.
2. High blood cholesterol and elevated blood triglycerides. When the level of protein albumin in the blood drops, the liver produces more albumin. At the same time, our liver releases more cholesterol and triglycerides.
3. Bad nutrition. Losing too much protein in your blood can cause malnutrition. This can lead to weight loss which can be masked by swelling. We may also have too few red blood cells (anemia), low blood protein levels and low vitamin D levels.
4. High blood pressure. Glomerular damage and the resulting build-up of excess body fluid can raise blood pressure.
5. Acute kidney damage. If the kidneys lose their ability to filter the blood due to damage to the glomeruli, waste products can build up quickly in the blood. If this happens, we may need emergency dialysis – an artificial way to remove extra fluid and waste from the blood – usually with a device with an artificial kidney (dialyzer).
6. Chronic kidney disease. Nephrotic syndrome can cause loss of kidney function over time. If kidney function drops low enough, we may need dialysis or a kidney transplant.
7. Infections. People with nephrotic syndrome have an increased risk of infection.

Nephrotic syndrome – diagnosis

A healthcare professional can diagnose nephrotic syndrome with urine tests. Urine tests show if we are losing too much protein in the urine.

Tests for the diagnosis of nephrotic syndrome

Urine test strip. This simple test checks the presence of albumin in the urine. Albumin in the urine is called albuminuria. The urine sample is collected in a container when you visit a healthcare professional’s office or laboratory. A healthcare professional places a strip of chemically treated paper, called a bayonet, into the urine for a test. The strip changes color if albumin is present in the urine.

To confirm a diagnosis of nephrotic syndrome, your healthcare professional may order one of these two urine tests:

1. 24-hour urine collection. For this study, we will need to collect urine samples for XNUMX hours. The healthcare professional will send the samples to the laboratory for analysis.
2. urine albumin to creatinine ratio (ACR). The ACR test uses a single urine sample to estimate the amount of albumin lost over 24 hours. The test measures both albumin and creatinine, a waste product of normal muscle breakdown.

A healthcare professional may also order blood tests to check for low blood protein levels and other problems with nephrotic syndrome. A blood test may show low levels of protein albumin and often lowered overall levels of protein in the blood. Loss of albumin is often associated with an increase in blood cholesterol and triglycerides.

Finding the cause of nephrotic syndrome may also include:

1. Kidney biopsy. Our doctor may recommend that you take a small sample of your kidney tissue for examination. During a kidney biopsy, the needle is inserted through the skin and into the kidney. Kidney tissue is collected and sent to a laboratory for testing.
2. Imaging tests, such as ultrasound of the kidneys.

See also: Laboratory diagnosis of kidney diseases

Nephrotic syndrome – treatment

Treatment of nephrotic syndrome includes treating any condition that may be causing the nephrotic syndrome. Your doctor may also recommend medications and dietary changes to help control symptoms or treat complications of nephrotic syndrome.

Medicines can fall into several categories.

1. Blood pressure medications. Medicines called angiotensin-converting enzyme inhibitors (ACE inhibitors) lower blood pressure and the amount of protein released in the urine. Drugs in this category include lisinopril (Prinvil, Qbrelis, Zestril), benazepril (Lotensin), captopril, and enalapril (Vasotec). Another group of drugs that work in a similar way is called angiotensin II receptor blockers (ARBs) and includes losartan (Cozaar) and valsartan (Diovan). Other medications such as renin inhibitors can also be used, although ACE inhibitors and ARBs are used first.
2. Diuretics. They help to control swelling by increasing fluid excretion by the kidneys. Diuretics usually include furosemide (Lasix). Others include spironolactone (Aldactone, Carospir) and thiazides such as hydrochlorothiazide or metolazone (Zaroxolyn).
3. Drugs to lower cholesterol. Statins can help lower cholesterol. However, it is unclear whether cholesterol-lowering drugs can improve outcomes in people with nephrotic syndrome, e.g. avoid a heart attack or reduce the risk of premature death. Statins include atorvastatin (Lipitor), fluvastatin (Lescol XL), lovastatin (Altoprev), pravastatin (Pravachol), rosuvastatin (Crestor, Ezallor), and simvastatin (Zocor).
4. Anticoagulants (anticoagulants). They can be prescribed to reduce the ability of blood to clot, especially if we have a blood clot. Anticoagulants include heparin, warfarin (Coumadin, Jantoven), dabigatran (Pradaxa), apixaban (Eliquis), and rivaroxaban (Xarelto).
5. Drugs that suppress the immune system. Medicines that control the immune system, such as corticosteroids, can reduce the inflammation associated with some conditions that can cause nephrotic syndrome. Medicines include rituximab (Rituxan), cyclosporine, and cyclophosphamide.

Nephrotic syndrome – diet

Changing your diet is crucial to avoid kidney damage. Since this disorder is due to protein loss, some people may counteract this loss by eating a protein-rich diet. However, a high-protein diet is not recommended for nephrotic syndrome. Too much protein is dangerous as it can damage nephrons (the functioning units of the kidneys) and cause kidney failure. A low to moderate protein intake is recommended, depending on the condition of your kidneys.

A low-sodium diet is also recommended in the case of nephrotic syndrome. Too much sodium in the diet can cause further fluid retention and salt retention, leading to unpleasant swelling and high blood pressure.

Since this disorder can also cause high blood fat levels, reducing your fat intake can prevent cardiovascular disease.

To help manage this condition, it’s important to understand what foods you should and shouldn’t eat.

Foods to eat on a diet with nephrotic syndrome:

1. lean meat (poultry, fish, shellfish);
2. dried beans;
3. peanut butter;
4. soy;
5. fresh or frozen fruit (apples, watermelons, pears, oranges, bananas);
6. fresh or frozen vegetables (green beans, lettuce, tomatoes);
7. low sodium canned vegetables;
8. potatoes;
9. rice;
10. whole grain products;
11. unsalted snacks (potato chips, nuts, popcorn);
12. cottage cheese;
13. tofu;
14. milk;
15. butter or margarine.

It is also worth following the tips below.

1. Be careful with your protein intake. The recommended protein intake for nephrotic syndrome is 1 gram (g) per kilogram of body weight per day. However, this amount may vary depending on the current health of your kidneys.
2. Limit or avoid using spices with the word “salt” in the name. They have a higher salt content than herbs and spices. If the recipe requires garlic salt, replace it with fresh garlic or garlic powder.
3. Prepare meals at home. Restaurant meals may have a higher salt content. Check the restaurant menu in advance and choose starters with less than 400 mg of sodium. Check if the restaurant can prepare the meal without salt.
4. Cook with healthy oils such as olive oil or coconut oil.
5. Choose fresh vegetables or canned vegetables that are sodium-free or low in sodium to reduce sodium intake.

See also: High-protein diets increase the risk of developing kidney disease

Nephrotic syndrome – prophylaxis

Some causes of nephrotic syndrome cannot be prevented. However, you can take measures to avoid damaging the glomeruli:

1. control high blood pressure and diabetes if you have it;
2. make sure you get vaccines for common infections, especially if you work with people suffering from hepatitis or other illnesses;
3. if your doctor prescribes antibiotics, take them as directed and finish each prescription, even if you feel better.