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Overview

What Is Nephrotic Syndrome?

Nephrotic syndrome is a group of symptoms caused by damage to the kidneys’ tiny filtering units. These damaged filters allow too much protein to pass into the urine, which can lower the protein level in the blood and cause swelling. This nephrotic syndrome definition applies to a condition that can affect both children and adults. Several kidney diseases and other health conditions can lead to it.

Symptoms

Nephrotic Syndrome Symptoms

  • Swelling (edema) may develop in the feet, ankles, legs, face, or abdomen.
  • Urine may look unusually foamy because it contains extra protein.
  • Weight gain may occur because the body is retaining fluid.
  • Tiredness may develop as fluid balance and blood protein levels change.
  • Reduced appetite can occur during illness.
  • Children may have swelling around the eyes, especially in the morning.

Causes

Causes of Nephrotic Syndrome

Injury to the glomeruli, the kidneys’ filtering units, can cause nephrotic-range proteinuria, meaning a very large amount of protein is lost in the urine. Albumin, an important blood protein, may also be lost, leading to low blood albumin and fluid buildup in the tissues. The causes of nephrotic syndrome may begin in the kidneys or result from a condition affecting the whole body.

PRIMARY KIDNEY CAUSES

These conditions start mainly in the kidneys and include minimal change disease, focal segmental glomerulosclerosis, and membranous nephropathy.

SECONDARY CAUSES

Conditions that can affect the kidneys include diabetes, lupus, certain infections, amyloidosis, and some medicines.

Risk Factors

Risk Factors for Nephrotic Syndrome

  • Diabetes can damage the kidney filters and increase the risk of nephrotic syndrome.
  • Lupus and other autoimmune diseases may injure the kidneys.
  • Certain infections can trigger kidney inflammation or other kidney damage.
  • A family history of kidney disease or an inherited kidney disorder may increase risk.
  • Childhood age is associated with some forms of nephrotic syndrome.
  • Older age may increase the likelihood of some underlying causes.
  • Exposure to medicines linked with kidney injury may increase risk.

Complications

Complications of Nephrotic Syndrome

  • Blood clots can form because nephrotic syndrome changes clotting proteins in the blood.
  • Infections may occur more easily when protective proteins are lost in the urine.
  • High blood pressure may develop or become harder to control.
  • High cholesterol can occur as the body responds to low blood protein levels.
  • Malnutrition may result from protein loss and reduced appetite.
  • Acute kidney injury can cause a sudden decline in kidney function.
  • Chronic kidney disease may develop if kidney damage persists.

SEEK PROMPT CARE

Possible complications need attention

Seek urgent medical care for sudden chest pain or shortness of breath, one-sided leg swelling, fever, or markedly reduced urination. These symptoms may signal a blood clot, infection, or serious kidney problem.

Diagnosis

How Nephrotic Syndrome Is Diagnosed

Clinicians look for heavy protein loss in the urine, low albumin in the blood, swelling, and signs of an underlying kidney or systemic disease. The evaluation also helps distinguish nephrotic syndrome from nephritic syndrome and identify the cause.

FeatureNephrotic syndromeNephritic syndrome
Main kidney-filter problemThe filter allows unusually large amounts of protein to pass into urine.Inflammation damages the filter and can impair filtration.
Heavy protein leakageA defining feature is heavy protein loss in the urine.Protein loss is usually less prominent than in nephrotic syndrome.
Inflammation and impaired filtrationInflammation may or may not be present, depending on the cause.Inflammation and reduced filtration are more typical features.
  • Urinalysis and urine protein measurements check for protein loss and other urine changes.
  • Blood tests measure albumin, cholesterol, kidney function, and signs of related conditions.
  • Kidney ultrasound or other imaging may be used when clinicians need to assess kidney structure.
  • Testing for underlying diseases may include evaluations for diabetes, lupus, infections, or other causes.
  • A kidney biopsy may be recommended in selected cases to identify the specific kidney disease.

Treatment & Management

Nephrotic Syndrome Treatment and Management

TREAT THE CAUSE

Treatment may include corticosteroids or other immune medicines when appropriate, along with care for diabetes, lupus, infection, or another underlying condition.

MANAGE COMPLICATIONS

Blood-pressure and protein-lowering medicines, diuretics for swelling, cholesterol treatment, and anticoagulation when clinically indicated can help manage effects of protein loss.

Supportive care may include individualized advice about sodium and fluid intake, adequate nutrition, infection prevention, and a review of medicines that could affect the kidneys. Nephrotic syndrome treatment is tailored to the cause, kidney function, symptoms, and risk of complications.

Outlook and Prognosis

Outlook and Prognosis

The outlook varies widely and depends on the cause, age, response to treatment, and kidney function. Some people enter remission, while some children experience relapses. Other forms persist or progress to chronic kidney disease, so ongoing follow-up is important rather than relying on a specific promised outcome.

  • The underlying diagnosis strongly influences the expected course.
  • Age can affect the pattern and response to treatment.
  • The amount of protein in the urine helps indicate disease activity.
  • Kidney function affects the risk of long-term kidney problems.
  • Response to treatment can improve the outlook.
  • Recurrence or repeated relapses may require continued monitoring.
  • Complications can affect health and long-term kidney function.

When Should You See a Doctor

When Should You See a Doctor?

  • Arrange a medical evaluation for new or unexplained swelling.
  • Ask a clinician about urine that repeatedly looks unusually foamy.
  • Seek evaluation for unexplained rapid weight gain.
  • Contact a clinician if urination becomes noticeably reduced.
  • Arrange medical assessment for possible nephrotic syndrome symptoms in a child.

EMERGENCY SYMPTOMS

Get immediate medical help

Call emergency services or go to an emergency department for severe shortness of breath, chest pain, coughing blood, sudden confusion, severe weakness, or one-sided painful leg swelling.

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