Overview

Membranous nephropathy (MEM-bruh-nus nuh-FROP-uh-thee) occurs when the small blood vessels in the kidney (glomeruli), which filter wastes from the blood, become damaged and thickened. As a result, proteins leak from the damaged blood vessels into the urine (proteinuria). For many, loss of these proteins eventually causes signs and symptoms known as nephrotic syndrome.

In mild cases, membranous nephropathy may get better on its own, without any treatment. As protein leakage increases, so does the risk of long-term kidney damage. In many, the disease ultimately leads to kidney failure. There's no absolute cure for membranous nephropathy, but successful treatment can lead to remission of proteinuria and a good long-term outlook.

Source: http://www.mayoclinic.com

Symptoms

Membranous nephropathy may develop gradually, so you may not suspect that anything is wrong. As you lose protein from your blood, swelling in your legs and ankles and weight gain from excess fluid can occur. Many people have lots of swelling from the very beginning of the disease, but others may not have any severe symptoms until they have advanced kidney disease.

Signs and symptoms of membranous nephropathy include:

• Swelling in the legs and ankles
• Weight gain
• Fatigue
• Poor appetite
• Urine that looks foamy
• High cholesterol
• Increased protein in the urine (proteinuria)
• Decreased protein in the blood, particularly albumin

When to see a doctor

Make an appointment with your doctor if you have:

• Blood in your urine
• Swelling in your legs and ankles that doesn't go away
• Increased blood pressure
• Sudden pain between your upper belly and middle back
• Sudden shortness of breath, which could be related to a blood clot complication

Source: http://www.mayoclinic.com

Causes

Often, membranous nephropathy results from some type of autoimmune activity. Your body's immune system mistakes healthy tissue as foreign and attacks it with substances called autoantibodies. These autoantibodies target certain proteins located in the kidney's filtering systems (glomeruli). This is known as primary membranous nephropathy.

Sometimes membranous nephropathy is brought on by other causes. When this happens, it's called secondary membranous nephropathy. Causes may include:

• Autoimmune disease, such as lupus erythematosus
• Infection with hepatitis B, hepatitis C or syphilis
• Certain medications, such as gold salts and nonsteroidal anti-inflammatory drugs
• Solid cancerous tumors or blood cancers

Membranous nephropathy may also occur along with other kidney diseases, such as diabetic nephropathy and rapidly progressive (crescentic) glomerulonephritis.

Source: http://www.mayoclinic.com

Diagnosis

Membranous nephropathy may not cause any signs or symptoms. Sometimes, it's diagnosed when a routine urine test — performed for another health reason — shows that you have high levels of protein in your urine (proteinuria).

If you do have signs or symptoms of protein in the urine, your doctor will ask questions about your medical history and perform a complete physical exam. Your blood pressure will be checked.

Blood, urine and imaging tests can tell your doctor how well your kidneys are working and diagnose membranous nephropathy. They can also help rule out other possible causes of your symptoms.

Tests that may be done include:

• A urine test (urinalysis). You may be asked to provide a urine sample so your doctor can measure how much protein is in your urine.
• Blood tests. A blood sample allows your doctor to check for high cholesterol, high triglycerides, high blood sugar and other factors that can affect the kidneys. A creatinine blood test gives information about your kidney function. Other blood tests can be done to check for autoimmune diseases or viral infections that can cause kidney damage, such as hepatitis B or C.
• Glomerular filtration rate (GFR) test. The GFR test estimates your level of kidney function and can help your doctor determine your stage of kidney disease.
• Antinuclear antibody (ANA) test. This blood tests looks for antinuclear antibodies, substances that attack your body's own tissues. High levels of antinuclear antibodies are a sign of an autoimmune disease.
• Kidney ultrasound or computed tomography (CT). Imaging scans allow your doctor to see the structure of your kidneys and urinary tract.
• Kidney biopsy. A doctor removes a small piece of your kidney to be examined under a microscope. A kidney biopsy is usually needed to confirm the diagnosis. It can tell your doctor the type of kidney disease you have, the amount of kidney damage and what treatments may work best.
• Anti-PLA2R antibody test. This new blood test looks for certain immune substances related to membranous nephropathy. It may help confirm or rule out the disease when a biopsy cannot be done. High levels of these antibodies are a sign of active disease. They've been linked to an increased risk of worsening kidney function.

Source: http://www.mayoclinic.com

Complications

Complications associated with membranous nephropathy include:

• High cholesterol. Levels of cholesterol and triglycerides are often high in people with membranous nephropathy, which greatly increases the risk of heart disease.
• Blood clots. With proteinuria, you may lose proteins that help prevent clotting from your blood into your urine. This makes you more prone to having blood clots develop in deep veins or blood clots that travel to your lungs.
• High blood pressure. Waste buildup in your blood (uremia) and salt retention can raise blood pressure.
• Infections. You're more susceptible to infections when proteinuria causes you to lose immune system proteins (antibodies) that protect you from infection.
• Nephrotic syndrome. High protein levels in the urine, low protein levels in the blood, high blood cholesterol, and swelling (edema) of the eyelids, feet and abdomen occur with this syndrome.
• Acute kidney failure. In cases of severe damage to the kidneys' filtering units (glomeruli), waste products may build up quickly in your blood. You may need emergency dialysis to remove extra fluids and waste from your blood.
• Chronic kidney disease. Your kidneys may gradually lose function over time to the point where you need dialysis or a kidney transplant.

Lifestyle and home remedies

Talk to your doctor about how to reduce your chances of developing kidney disease. Your doctor may suggest that you:

• Have regular checkups
• Follow your prescribed treatment for diabetes or high blood pressure
• Lose excess weight by following a healthy diet and regular exercise program
• Stop smoking, if you are a smoker
• Limit use of over-the-counter pain medications
• Make changes in your diet, such as eating less salt and less protein
• Limit your intake of alcohol

Source: http://www.mayoclinic.com

Risk factors

Factors that can increase your risk of membranous nephropathy include:

• Having a medical condition that can damage your kidneys. Certain diseases and conditions increase your risk of developing membranous nephropathy, such as lupus and other autoimmune diseases.
• Use of certain medications. Examples of medications that can cause membranous nephropathy include nonsteroidal anti-inflammatory drugs and gold salts.
• Exposure to certain infections. Examples of infections that increase the risk of membranous nephropathy include hepatitis B, hepatitis C and syphilis.
• Genetic background. Certain genetic factors make it more likely that you'll develop membranous nephropathy.

Source: http://www.mayoclinic.com