Nephrotic Syndrome
What is nephrotic syndrome? What does nephrotic-range proteinuria mean? Learn all about the causes, symptoms, diagnostic methods, and treatments for excessive protein in the urine.
Symptoms and Causes
Nephrotic syndrome is a collection of symptoms caused by a disorder affecting the glomeruli (tiny blood vessels in the kidneys with pores similar to a sieve). These structures filter waste and excess water from the blood while preventing proteins and blood cells from passing through. As a result, urine contains high levels of protein, blood protein levels drop, cholesterol increases, and swelling (edema) develops in certain areas of the body.
Although nephrotic syndrome can affect people of all ages, it is more common in children, especially between 18 months and 4 years old. This condition may develop gradually or appear suddenly.
The prognosis of nephrotic syndrome depends on its underlying cause. In cases where the cause is treatable, particularly in childhood, symptoms can completely resolve.
Symptoms
The most common symptoms of nephrotic syndrome include:
- Fluid retention
- Abdominal pain
- Fatigue
- Foamy urine (beer-like appearance)
- Loss of appetite
- Swelling or edema starting in the legs and progressing upward
- General discomfort
Causes
The most common cause of nephrotic syndrome is glomerular damage, which enlarges the pores and allows proteins to leak through. This abnormality can have different origins, leading to two classifications of the disease:
- Primary nephrotic syndrome: May be due to a genetic abnormality or be idiopathic, meaning its cause is unknown.
- Secondary nephrotic syndrome: Caused by other diseases, including:
- Diabetic nephropathy: Kidney damage caused by diabetes mellitus.
- Minimal change disease: The most common cause in children, leading to impaired kidney function despite no visible structural changes.
- Focal segmental glomerulosclerosis: Causes scarring in certain kidney blood vessels.
- Membranous nephropathy: Can be primary or secondary to systemic lupus erythematosus, hepatitis B, malaria, or certain cancers. It results in immune system deposits (antibodies) accumulating in the glomerular membranes, thickening and distorting them, allowing protein to pass through.
- Amyloid nephropathy: Caused by amyloidosis, a buildup of proteins in the blood vessels.
Risk Factors
The main factors that increase the likelihood of developing nephrotic syndrome include:
- Diseases such as diabetic kidney disease, lupus, cancer, or amyloidosis.
- Infections such as hepatitis C and B, malaria, or HIV.
- Medications such as nonsteroidal anti-inflammatory drugs (NSAIDs) or antibiotics.
Complications
Nephrotic syndrome can lead to:
- Edema or swelling in certain parts of the body
- Anemia
- Poor nutrition
- Blood clots
- High cholesterol
- High blood pressure
- Chronic kidney disease
- Infections
Prevention
Although nephrotic syndrome is often unavoidable, certain measures can help maintain glomerular health, such as keeping blood pressure low, controlling blood sugar levels in diabetes, and staying up to date with common vaccinations.
Which Doctor Treats Nephrotic Syndrome?
Nephrology specialists and pediatric kidney specialists are the doctors responsible for diagnosing and treating nephrotic syndrome.
Diagnosis
To diagnose nephrotic syndrome, the following tests are performed:
- Medical history and symptom evaluation.
- Urinalysis: Detects protein levels or blood in the urine.
- Blood test: Measures albumin and creatinine levels, including blood urea nitrogen (BUN).
- Kidney biopsy: Determines the cause of nephrotic syndrome by analyzing a tissue sample.
Treatment
In most cases, treatment for nephrotic syndrome focuses on relieving symptoms and addressing the underlying cause. The most effective approaches include:
- Medication: Corticosteroids, immunosuppressants, antihypertensives, diuretics, or anticoagulants.
- Lifestyle changes: Recommendations include reducing fat and cholesterol intake, consuming lean or plant-based proteins, avoiding salt, and limiting fluid consumption.
