Nephrotic syndrome: symptoms, causes and diagnosis

Medical disclaimer: This page is general health information for education only. It is not medical advice and is not a substitute for diagnosis or treatment by a qualified health professional. It has not been reviewed by a clinician. In an emergency, call 911 or your local emergency number.

What is nephrotic syndrome?

Nephrotic syndrome is a group of symptoms that indicate your kidneys are not working properly, usually because protein leaks into your urine. It is not one single disease. Many different conditions can cause it, in both children and adults.

Your kidneys contain about a million tiny filtering units. Each one has a filter called a glomerulus (plural: glomeruli). Healthy glomeruli keep protein in your blood and let waste pass into your urine. The National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) explains that nephrotic syndrome usually happens when the glomeruli are inflamed, so too much protein leaks from the blood into the urine.

This page explains the signs, common causes, and the tests clinicians use. It sits within our library of health conditions. This page covers adults and children in general terms only. It cannot tell you whether you or your child has nephrotic syndrome or what is causing it.

Nephrotic syndrome symptoms and lab signs

Nephrotic syndrome has four core findings: too much protein in the urine, low blood albumin, swelling, and high blood fats.

NIDDK lists the four core findings this way:

• Proteinuria: too much protein in your urine.
• Hypoalbuminemia: low levels of a blood protein called albumin.
• Edema: swelling in parts of your body.
• Hyperlipidemia: high levels of cholesterol and other fats in your blood.

Symptoms you may notice

Swelling (edema) is the most common symptom of nephrotic syndrome, according to MedlinePlus. Other symptoms NIDDK and MedlinePlus list include:

• Puffy eyelids, or swelling in the face and around the eyes.
• Swelling in the legs, ankles, feet, or belly area.
• Foamy urine.
• Weight gain from holding on to extra fluid.
• Tiredness.
• Loss of appetite.

In children, swelling around the eyes is the most common sign of nephrotic syndrome. NIDDK notes this swelling is usually worse in the morning. When mild, it may be confused with seasonal allergies.

Lab thresholds clinicians use

Doctors confirm the protein loss with lab tests. A review on the National Library of Medicine’s NCBI Bookshelf gives this wording:

• Nephrotic-range proteinuria is “the urinary loss of 3 grams or more of proteins per 24 hours.”
• On a single spot urine sample, it is “the presence of 2 g of protein per gram of urinary creatinine.”
• “Serum albumin often is less than the normal range of 3.5 to 4.5 g/dL.”

These figures come from the StatPearls review of nephrotic syndrome. Lab ranges can differ between laboratories and between adults and children. Only your care team can interpret your own results.

What causes nephrotic syndrome?

Nephrotic syndrome is caused by diseases that damage the kidney’s filters, either kidney diseases alone or conditions that affect the whole body.

Diseases that affect only the kidneys are called primary causes. NIDDK names the most common primary causes:

• Focal segmental glomerulosclerosis (FSGS): scarring of some glomeruli. It is the most common cause in Black adults.
• Membranous nephropathy: protein buildup in a layer of the kidney filter. It is the most common cause in white adults.
• Minimal change disease: the main cause of nephrotic syndrome in children.

Causes linked to other conditions are called secondary causes. NIDDK lists:

• Diabetes.
• Lupus.
• Amyloidosis, a buildup of abnormal proteins in organs.
• Infections such as HIV, hepatitis B, and hepatitis C.
• Some allergic reactions.
• Some medicines, such as nonsteroidal anti-inflammatory drugs (NSAIDs).
• Genetic disorders that affect the kidneys.

MedlinePlus also lists cancer, multiple myeloma, and immune disorders among possible causes. If you live with a long-term condition like type 1 or type 2 diabetes, ask how your kidneys are being checked. These lists are not complete. A clinician needs tests to find the cause in any one person.

How is nephrotic syndrome diagnosed?

Nephrotic syndrome is diagnosed with urine tests that show heavy protein loss, followed by tests to find the cause.

NIDDK describes these urine tests:

• Urine dipstick test: a treated paper strip changes color if albumin is in the urine.
• 24-hour urine collection: you collect all your urine for 24 hours for lab analysis.
• Urine albumin-to-creatinine ratio (UACR): a single sample estimates the albumin lost in 24 hours.

Blood tests check for low blood protein and other problems linked to nephrotic syndrome. MedlinePlus lists blood tests such as albumin, blood urea nitrogen (BUN), and creatinine, which show how well the kidneys work.

To find the cause, clinicians may order more blood tests, imaging such as a kidney ultrasound, or a kidney biopsy. A biopsy removes a tiny piece of kidney tissue to look at under a microscope. Many children with nephrotic syndrome will not need a kidney biopsy, according to NIDDK. This page cannot tell you which tests you need. For help making sense of lab reports, see our guide to reading health information.

Possible complications

Nephrotic syndrome can lead to blood clots, infections, high blood pressure, and short or long-term kidney problems.

NIDDK lists these complications:

• Blood clots that can block blood vessels (thrombosis).
• A higher risk of infection, from losing proteins that help fight germs.
• High blood pressure.
• Kidney problems, including chronic kidney disease and kidney failure.

This list does not predict what will happen to any one person. Your care team can explain which risks apply to your cause.

When to get emergency help

Signs of a blood clot in the lungs, called a pulmonary embolism, include trouble breathing, chest pain that worsens with a deep breath or cough, a fast or irregular heartbeat, coughing up blood, and fainting. These signs come from the CDC’s guide to blood clots. MedlinePlus advises going to the emergency room or calling 911 for symptoms of a pulmonary embolism. MedlinePlus also advises calling 911 for seizures in a person with nephrotic syndrome.

The CDC lists swelling, pain or tenderness, warmth, and redness in a limb as signs of a clot in a deep vein. It advises seeing your doctor as soon as possible if you notice them.

How care is approached

Care for nephrotic syndrome aims to treat the underlying cause, ease symptoms, and prevent complications.

Treatment varies according to symptoms, causes, and the extent of kidney damage, NIDDK explains. Medicine classes that NIDDK and MedlinePlus name include:

• ACE inhibitors or angiotensin II receptor blockers (ARBs), which can lower blood pressure and reduce protein loss.
• Diuretics (water pills), which help the kidneys remove extra fluid.
• Statins, which lower cholesterol, in some cases.
• Blood thinners, usually only if a clot develops.
• Corticosteroids or other medicines that calm the immune system, for some underlying causes.

NIDDK advises that people with nephrotic syndrome receive the pneumococcal vaccine and yearly flu shots. Your clinician may also suggest limiting salt and fluids to help control swelling. The National Kidney Foundation notes that eating a high-protein diet does not help and may make matters worse.

The outlook differs from person to person. Some people recover, and others develop long-term kidney disease. This section describes general approaches only. It does not replace a plan from your own kidney specialist (nephrologist), and you should not change any medicine or diet without talking to your care team.

Questions to bring to your appointment

Writing questions down before a visit helps you use the time well. Our guide on how to prepare for a medical appointment has more tips. These questions are a starting point and do not cover every situation.

• What is causing my nephrotic syndrome, and how will we find out?
• What did my urine protein and blood albumin results show?
• Do I need a kidney biopsy, and what would it tell us?
• What signs of a blood clot or infection should I watch for?
• Should I limit salt, fluids, or anything else in my diet?
• Which vaccines do you recommend for me, and when?