Nephrotic Syndrome

Nephrotic syndrome is a kidney disorder where your kidneys let too much protein pass into your urine. This happens because the tiny filters in your kidneys, called glomeruli, are damaged. It often leads to swelling in your body, foamy urine, and other symptoms. Treatment focuses on managing symptoms and addressing the underlying cause.

What is Nephrotic Syndrome?

Nephrotic syndrome is a kidney disorder that causes your body to pass too much protein into your urine. This occurs when the tiny filters in your kidneys, called glomeruli, become damaged and cannot properly keep protein in your blood. This condition can lead to swelling, foamy urine, and other health problems.

Your kidneys are vital organs that filter waste and excess water from your blood, creating urine. Inside each kidney are millions of tiny filtering units called glomeruli (pronounced glo-MARE-yoo-lie). These glomeruli normally prevent large molecules like protein from leaving your blood and entering your urine. When you have nephrotic syndrome, these glomeruli are damaged. This damage allows a significant amount of protein, particularly a protein called albumin, to leak from your blood into your urine. This loss of protein from the blood can lead to a range of symptoms and complications throughout your body. The amount of protein lost in the urine is a key feature of nephrotic syndrome. This condition is not a disease itself but rather a group of symptoms that point to kidney damage. It can affect both children and adults. (MedlinePlus, Mayo Clinic)

Symptoms

The main symptoms of nephrotic syndrome include severe swelling (edema), especially around your eyes, ankles, and feet, and foamy urine. You might also notice weight gain from fluid retention, feel very tired, and lose your appetite. These symptoms happen because your kidneys are losing too much protein.

Swelling, or edema, is one of the most noticeable symptoms. It often appears first around your eyes, particularly in the morning, and later in your legs, ankles, and feet. Fluid can also build up in your abdomen, making it appear swollen. This swelling occurs because losing protein from your blood reduces the blood's ability to hold fluid in your blood vessels, causing it to leak into your body tissues. (MedlinePlus, Mayo Clinic) Another common sign is foamy urine. This foam is caused by the high levels of protein present in your urine. You might also experience unexplained weight gain due to the extra fluid your body is retaining. Other general symptoms can include feeling very tired (fatigue) and a decreased desire to eat (loss of appetite). (MedlinePlus, Mayo Clinic)

Causes & risk factors

Nephrotic syndrome is caused by damage to the kidney's filtering units (glomeruli), which can be due to a primary kidney disease or another underlying health condition. Risk factors include having diseases like diabetes, lupus, or amyloidosis, certain infections such as hepatitis B or HIV, and using some medications like nonsteroidal anti-inflammatory drugs (NSAIDs).

Causes of nephrotic syndrome are generally divided into two categories: primary and secondary. Primary causes are diseases that directly affect the kidneys and their glomeruli. The most common primary causes include minimal change disease, which is the leading cause in children, focal segmental glomerulosclerosis (FSGS), and membranous nephropathy. (MedlinePlus, Mayo Clinic) Secondary causes are other medical conditions that can damage the kidneys and lead to nephrotic syndrome. These include long-term conditions like diabetes, which can harm kidney filters over time, and autoimmune diseases such as lupus. Other secondary causes can be amyloidosis, certain infections like hepatitis B, hepatitis C, HIV, or malaria, and some types of cancer. (MedlinePlus, Mayo Clinic) Certain medications can also increase your risk, including nonsteroidal anti-inflammatory drugs (NSAIDs) and some drugs used to treat other conditions. If you have any of these underlying conditions or are taking these medications, your risk of developing nephrotic syndrome may be higher. (MedlinePlus, Mayo Clinic)

How it's diagnosed

Diagnosing nephrotic syndrome usually involves urine and blood tests. A urine test checks for high levels of protein and fat, while blood tests measure protein levels (especially albumin), cholesterol, and triglycerides. To confirm the diagnosis and identify the specific cause of kidney damage, your doctor may recommend a kidney biopsy.

The first step in diagnosis is typically a urine test, often a 24-hour urine collection, to measure the exact amount of protein being lost. High levels of protein in the urine (proteinuria) are a hallmark of nephrotic syndrome. The urine may also show the presence of fat. (MedlinePlus, Mayo Clinic) Blood tests are also crucial. These tests will usually show low levels of albumin, a key protein, in your blood (hypoalbuminemia) because it's being lost in the urine. Blood tests can also reveal high levels of cholesterol and triglycerides, which are fats in the blood. These changes in blood chemistry help confirm the diagnosis. (MedlinePlus, Mayo Clinic) To determine the specific type of kidney damage and its underlying cause, your doctor may recommend a kidney biopsy. During this procedure, a small piece of kidney tissue is removed with a needle and examined under a microscope. This biopsy is often essential for guiding the most effective treatment plan. (MedlinePlus, Mayo Clinic)

Treatment options

Treatment for nephrotic syndrome focuses on managing symptoms, preventing complications, and addressing the underlying cause of kidney damage. Medications may include blood pressure drugs to reduce protein in urine, diuretics to lessen swelling, and statins to lower cholesterol. Immunosuppressants are often used if the cause is inflammatory or autoimmune.

One primary goal of treatment is to reduce the amount of protein leaking into your urine and control blood pressure. Medications such as angiotensin-converting enzyme (ACE) inhibitors or angiotensin receptor blockers (ARBs) are often prescribed for this purpose. These drugs help protect your kidneys and can also lower blood pressure. (MedlinePlus, Mayo Clinic, Cochrane Library) To manage swelling, your doctor may prescribe diuretics, often called "water pills." These medications help your kidneys remove excess fluid from your body, reducing edema. If you have high cholesterol, which is common with nephrotic syndrome, cholesterol-reducing medications called statins may be used to lower your risk of heart disease. (MedlinePlus, Mayo Clinic) For cases where the kidney damage is caused by inflammation or an autoimmune condition, immunosuppressant medications may be necessary. These can include corticosteroids (like prednisone), or other drugs such as cyclosporine, tacrolimus, or cyclophosphamide. These medications work by calming your immune system to reduce damage to the kidney filters. Your doctor might also recommend dietary changes, such as reducing salt intake to help with swelling and limiting saturated fats. (MedlinePlus, Mayo Clinic, Cochrane Library)

Recovery & outlook

The recovery and long-term outlook for nephrotic syndrome vary greatly depending on its underlying cause, how well it responds to treatment, and whether complications develop. Some forms, like minimal change disease, often respond well to medication, especially in children. Others, such as focal segmental glomerulosclerosis, may progress to chronic kidney disease or kidney failure.

For many people, especially children with minimal change disease, nephrotic syndrome can go into remission with appropriate treatment, often involving corticosteroids. In these cases, symptoms resolve, and kidney function may return to normal. However, relapses can occur, requiring further treatment. (MedlinePlus, Mayo Clinic, Cochrane Library) For other causes, such as focal segmental glomerulosclerosis (FSGS) or certain secondary causes, the condition may be more challenging to treat and can sometimes lead to more serious outcomes. Over time, persistent kidney damage can progress to chronic kidney disease, and in some cases, end-stage kidney disease, which may require dialysis or a kidney transplant. (MedlinePlus, Mayo Clinic) Managing complications is also key to outlook. Nephrotic syndrome increases the risk of blood clots, infections, and high blood pressure. Regular monitoring and proactive treatment of these issues can improve long-term health. Your healthcare team will work with you to develop a personalized treatment plan and monitor your kidney function closely. (MedlinePlus, Mayo Clinic)

When to see a doctor

You should see a doctor if you notice any signs or symptoms of nephrotic syndrome, such as unexplained swelling around your eyes, ankles, or feet, or if your urine appears unusually foamy. Prompt medical attention is important for diagnosis and to prevent potential complications.

It is crucial to contact your healthcare provider if you develop persistent swelling, especially if it's new or worsening. Swelling that doesn't go away, particularly in your legs, feet, or around your eyes, warrants medical evaluation. Similarly, if you consistently notice that your urine is very foamy, this could indicate high levels of protein and should be checked by a doctor. (MedlinePlus, Mayo Clinic) Other symptoms like unexplained fatigue, significant weight gain due to fluid retention, or a loss of appetite should also prompt a visit to your doctor. Early diagnosis and treatment of nephrotic syndrome can help manage symptoms, prevent serious complications like blood clots or severe infections, and potentially slow the progression of kidney damage. Do not wait for symptoms to become severe before seeking medical advice. (MedlinePlus, Mayo Clinic)

Frequently asked questions

Can nephrotic syndrome be cured?

Whether nephrotic syndrome can be "cured" depends on its underlying cause. Some forms, like minimal change disease, can go into long-term remission with treatment, meaning symptoms disappear and kidney function improves significantly. However, other causes may require ongoing management and might not have a complete cure, though treatments can control the condition. (MedlinePlus, Mayo Clinic)

Is nephrotic syndrome hereditary?

Most cases of nephrotic syndrome are not directly hereditary. However, some specific genetic mutations can cause certain types of primary nephrotic syndrome, such as some forms of focal segmental glomerulosclerosis (FSGS). If there's a family history of kidney disease, it's important to discuss this with your doctor. (MedlinePlus, Mayo Clinic)

What kind of diet should I follow with nephrotic syndrome?

A low-salt (sodium) diet is often recommended to help reduce swelling. Your doctor may also advise a low-fat diet to help manage high cholesterol levels. While protein is lost in the urine, your doctor will guide you on appropriate protein intake, as too much or too little can be problematic. Always follow your healthcare provider's specific dietary recommendations. (MedlinePlus, Mayo Clinic)

Can nephrotic syndrome lead to kidney failure?

Yes, in some cases, nephrotic syndrome can lead to kidney failure, especially if the underlying cause is severe or doesn't respond well to treatment. Conditions like focal segmental glomerulosclerosis (FSGS) have a higher risk of progressing to chronic kidney disease or end-stage kidney disease, which may require dialysis or a kidney transplant. (MedlinePlus, Mayo Clinic)

Are there any complications I should be aware of?

Yes, nephrotic syndrome can lead to several complications. These include an increased risk of blood clots, high cholesterol, high blood pressure, acute kidney injury, and infections due to the loss of antibodies in the urine. Malnutrition can also occur due to protein loss. Your doctor will monitor you for these issues. (MedlinePlus, Mayo Clinic)

How often do children with nephrotic syndrome relapse?

Children with minimal change disease, the most common type of nephrotic syndrome in children, often respond well to corticosteroids. However, relapses are common, with many children experiencing multiple episodes. The frequency of relapses varies greatly among individuals, and some children may require ongoing or repeated treatment. (Cochrane Library)

Sources

• MedlinePlus — Nephrotic Syndrome
• Mayo Clinic — Nephrotic Syndrome
• Cochrane Library — Nephrotic Syndrome