Membranous Nephropathy
What is Membranous Nephropathy?
Membranous nephropathy is a kidney disease that affects the tiny filters in your kidneys called glomeruli. These filters normally keep protein in your blood while removing waste. When you have membranous nephropathy, immune complexes deposit on the glomerular membranes. This causes the filters to become damaged and leak protein into your urine.
The condition is one of the most common causes of nephrotic syndrome in adults. Nephrotic syndrome means you lose large amounts of protein in your urine, which leads to swelling and other symptoms. Some people with membranous nephropathy experience spontaneous remission, meaning the disease improves on its own. Others develop progressive kidney damage over time if left untreated.
Membranous nephropathy can be primary, meaning it happens on its own, or secondary to other conditions. Secondary causes include autoimmune diseases, infections, certain medications, and some cancers. Understanding the root cause helps guide treatment and improve outcomes. Early detection through blood and urine testing allows you to monitor kidney function and protein levels before serious damage occurs.
Symptoms
- Swelling in the legs, ankles, feet, or around the eyes
- Foamy or frothy urine due to high protein levels
- Unexplained weight gain from fluid retention
- Fatigue and general weakness
- Loss of appetite
- High cholesterol levels on blood tests
- Blood clots in veins or lungs
- High blood pressure
Many people have no obvious symptoms early on, especially if protein loss is mild. The condition is often discovered during routine urine tests. Symptoms typically develop gradually as protein loss increases over weeks or months.
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Causes and risk factors
Membranous nephropathy happens when immune complexes deposit in the kidney filters. In primary membranous nephropathy, the immune system mistakenly creates antibodies against proteins in the kidney. The most common target is a protein called PLA2R found on kidney cells. In secondary cases, the condition results from autoimmune diseases like lupus, infections like hepatitis B or C, certain cancers, or medications including NSAIDs and gold salts.
Risk factors include being over 40 years old, male gender, and having autoimmune conditions or chronic infections. Some people have genetic factors that increase susceptibility. Lifestyle factors like smoking and obesity may worsen kidney damage once the disease develops. Identifying whether your case is primary or secondary helps determine the best treatment approach and address any underlying conditions.
How it's diagnosed
Membranous nephropathy is diagnosed through a combination of urine tests, blood tests, and often a kidney biopsy. Urine tests measure protein levels to assess disease severity. Blood tests evaluate kidney function and look for underlying causes. A kidney biopsy provides definitive diagnosis by showing the characteristic immune deposits under a microscope.
Rite Aid offers blood testing that measures key biomarkers for kidney health. Cystatin C provides accurate kidney function assessment even when protein levels vary. Urine protein testing helps detect high protein loss and monitor disease activity. Regular testing allows you to track kidney function over time and catch changes early. These tests are available through our preventive health service at Quest Diagnostics locations nationwide.
Treatment options
- Blood pressure medications, especially ACE inhibitors or ARBs, to reduce protein loss and protect kidneys
- Diuretics to reduce swelling by removing excess fluid
- Cholesterol-lowering medications like statins
- Blood thinners if you develop blood clots or are at high risk
- Immunosuppressive medications like corticosteroids, cyclosporine, or rituximab for severe or progressive cases
- Low-salt diet to reduce fluid retention and blood pressure
- Moderate protein intake as recommended by your doctor
- Regular exercise and maintaining a healthy weight
- Avoiding NSAIDs and other medications that can harm kidneys
- Treating any underlying conditions causing secondary membranous nephropathy
Concerned about Membranous Nephropathy? Get tested at Rite Aid.
- Simple blood draw at your nearest lab
- Results in days, not weeks
- Share results with your doctor
Frequently asked questions
Primary membranous nephropathy occurs when your immune system attacks kidney proteins directly without an identifiable cause. Secondary membranous nephropathy develops due to other conditions like autoimmune diseases, infections, cancers, or certain medications. Determining which type you have is important because treating the underlying condition can resolve secondary cases.
Yes, about one-third of people with membranous nephropathy experience spontaneous remission, meaning the disease improves without treatment. This typically happens within the first few years after diagnosis. However, another third develop progressive kidney damage, so regular monitoring with blood and urine tests is essential to track disease activity and kidney function.
Testing frequency depends on your disease severity and treatment status. Most people need urine protein and kidney function tests every 3 to 6 months. Your doctor may recommend more frequent testing if you start new medications or if your condition is changing. Regular monitoring helps detect progression early and assess whether treatments are working.
No, but they are closely related. Membranous nephropathy is a specific kidney disease that damages the glomerular filters. Nephrotic syndrome is a collection of symptoms including high urine protein, low blood protein, high cholesterol, and swelling. Membranous nephropathy is one of the most common causes of nephrotic syndrome in adults.
Foamy or frothy urine indicates high protein levels in your urine. Protein makes urine bubble similar to soap in water. This happens because damaged kidney filters leak protein that should stay in your blood. Foamy urine is often one of the first noticeable signs of membranous nephropathy.
Yes, diet plays an important role in managing the condition. A low-salt diet helps reduce fluid retention and blood pressure. Your doctor may recommend moderate protein intake to reduce strain on your kidneys. Limiting saturated fats helps manage high cholesterol. These dietary changes work best when combined with medications and regular monitoring.
Cystatin C provides more accurate kidney function assessment when you have membranous nephropathy. Unlike creatinine, Cystatin C is not affected by muscle mass, protein intake, or the fluid retention and swelling common in this condition. This makes it especially useful for monitoring kidney function as protein levels fluctuate during treatment or remission.
NSAIDs like ibuprofen and naproxen are common culprits. Gold salts used for rheumatoid arthritis, penicillamine, and some cancer drugs can also trigger the condition. If you have membranous nephropathy, tell all your doctors about your diagnosis so they can avoid prescribing medications that might worsen kidney damage.
Not necessarily. About one-third of people experience spontaneous remission, and many others respond well to treatment. However, about one-third do develop progressive kidney failure over 10 to 20 years. Regular monitoring with blood tests like Cystatin C helps detect declining kidney function early so treatment can be adjusted to slow progression.
Yes, relapse is possible even after successful treatment. Studies show that 30 to 40 percent of people who achieve remission experience a relapse within several years. This is why ongoing monitoring with urine protein and kidney function tests is important even after your symptoms improve. Early detection of relapse allows for prompt treatment adjustments.