OVERVIEW

What is membranous nephropathy?

Membranous nephropathy (MN) refers to a type of glomerular disease characterized primarily by the deposition of immune complexes beneath the glomerular basement membrane in the kidney, leading to pathological changes in the basement membrane.

It manifests as nephrotic syndrome (proteinuria, hypoalbuminemia, hyperlipidemia, and edema).

Is membranous nephropathy common?

Membranous nephropathy is relatively common and ranks as the second most prevalent primary glomerular disease in China.

SYMPTOMS

What are the symptoms of membranous nephropathy?

Edema is common, starting from the eyelids and gradually spreading throughout the body. Pressing the swollen area leaves a pit that slowly returns to normal. Some patients may have recent bacterial or viral infections. The condition is primarily detected through tests showing high urine protein, hypoalbuminemia, and hyperlipidemia.

Can membranous nephropathy heal on its own? Can it progress to kidney failure?

Some patients may experience spontaneous remission, while others may see disease progression, even leading to kidney failure. Treatment options—such as observation, general therapy, or immunotherapy—should be chosen based on individual conditions. Patients should adhere to regular treatment, maintain healthy lifestyle habits, and undergo periodic check-ups to slow disease progression.

What complications can membranous nephropathy cause?

The most significant complication is an increased risk of renal vein thrombosis. It may also lead to other nephritis, kidney failure, or infections.

CAUSES

What are the causes of membranous nephropathy?

Most cases have no clear cause and are referred to as primary or idiopathic membranous nephropathy. Some cases are secondary to certain diseases, such as infections, tumors, medications, toxins, and autoimmune diseases. Among these, hepatitis B virus infection, systemic lupus erythematosus, Sjögren's syndrome, and malignant tumors are relatively common causes of secondary membranous nephropathy.

Is membranous nephropathy hereditary?

It has some genetic correlation.

Can membranous nephropathy occur in children or young adults?

It mostly occurs in adults and is rare in children.

Which populations are more commonly affected by membranous nephropathy?

It primarily occurs in adults, with males being more affected than females.

What factors influence the progression of membranous nephropathy?

Patients with membranous nephropathy are more likely to experience disease progression and poorer outcomes under the following conditions:

• Older age at onset, particularly over 50 years;

• Male gender;

• Severe proteinuria, especially with protein excretion > 8–10 g/d;

• Elevated serum creatinine at the time of diagnosis.

DIAGNOSIS

What tests might be needed for the diagnosis of membranous nephropathy?

Initial tests such as blood tests, urine tests, and kidney function tests are required. Under current medical conditions, anti-PLA2R antibodies can also be tested, as this antibody is positive in 70% of patients with primary membranous nephropathy.

The diagnosis of membranous nephropathy should be confirmed by a kidney biopsy whenever possible. Specifically, a small piece of kidney tissue is extracted under ultrasound guidance for laboratory examination.

Which diseases can membranous nephropathy be easily confused with?

First, it must be differentiated from other kidney diseases. Second, it is necessary to determine whether it is caused by other underlying conditions, such as tumors, hepatitis, or certain medications (e.g., penicillamine, gold preparations), which can also lead to secondary membranous nephropathy.

TREATMENT

Which department should I visit for membranous nephropathy?

Nephrology.

When should patients with membranous nephropathy seek medical attention?

During outpatient treatment or observation, if symptoms such as recurrence or complications (e.g., fever, cough, sputum, abdominal pain, diarrhea, frequent urination, painful urination) or a significant decrease in urine output occur, hospitalization for re-examination and treatment is recommended.

How is membranous nephropathy treated?

Treatment depends on the patient's specific condition:

• For patients with normal renal function and proteinuria <4 g/24 h, bed rest, symptomatic treatment (controlling blood pressure, lipids, and proteinuria), and complication prevention are usually required.
• Patients with proteinuria >4 g/day accompanied by renal dysfunction or high-risk patients with proteinuria >8 g/day should receive immunotherapy.

What are the common side effects of immunotherapy for membranous nephropathy?

Possible side effects include:

• Drug-induced Cushing's syndrome: Long-term steroid use may cause symptoms resembling Cushing's syndrome, such as weight gain, rounded face, central obesity, skin striae, acne, hypertension, secondary diabetes, and osteoporosis.
• Increased infection risk: Steroids lower immunity, making infections more likely. Preventive measures include avoiding cold exposure and crowded places. Seek prompt medical attention if infection signs appear.
• Ulcer induction: High-dose, long-term steroid use may damage gastric mucosa, leading to ulcers. Seek immediate medical help if upper abdominal pain or black stools occur.
• Osteoporosis: Common in patients on long-term, high-dose steroids. Calcium and vitamin D supplementation and regular follow-ups are advised.
• Aseptic osteonecrosis.

Do patients with membranous nephropathy need follow-ups? How often?

Long-term monitoring is necessary:

• During medication, visit the clinic every 1–2 weeks to monitor proteinuria, renal function, and complications. Pediatric patients should also track growth and development.
• For patients off medication or not requiring immunotherapy, monitor every 3 months for 2 years, then every 6 months to assess disease progression.

DIET & LIFESTYLE

What should patients with membranous nephropathy pay attention to in their daily life and diet?

• Get adequate rest, avoid overexertion, and prevent infections.

• Ensure sufficient calorie intake and maintain a low-protein diet.

• Avoid medications that may harm the kidneys, such as gentamicin, streptomycin, tetracycline, phenylbutazone, phenacetin, paracetamol, and unproven herbal remedies.

Does membranous nephropathy affect fertility?

Female patients with kidney disease who wish to conceive need a comprehensive risk assessment, as pregnancy increases the burden on the kidneys and may lead to disease recurrence or worsening kidney function. Generally, pregnancy should be considered only after the disease has been stable and under control for 1–2 years.

PREVENTION

Is there any way to prevent membranous nephropathy?

The exact cause of membranous nephropathy is still unclear, but it may be related to abnormalities in the patient's immune function. Therefore, there are no effective preventive measures.