An autoimmune disorder in which the immune system mistakenly attacks specific small filters in the kidneys is called membranous nephropathy (MN). Normally, kidneys have small filters that help clean waste products from the blood. Without treatment, MN may lead to permanent kidney damage. Doctors often prescribe different treatments because they depend on the type and cause of MN.
In other words, membranous nephropathy is a condition in which the immune system attacks the glomeruli (tiny filters in the kidneys). Each kidney has thousands of these filters that help clean waste from the blood. In people with MN, these glomeruli become inflamed, which affects the ability of the kidneys to filter blood.
Moreover, this autoimmune condition may develop suddenly or slowly over time. There are a lot of people who have had this condition for years but do not know about it because they do not have symptoms. In addition, this disorder is a type of glomerular disease, and it is also called membranous glomerulopathy or membranous glomerulonephritis.
This condition occurs rarely and affects about 1 in every 5,000 people. Children are rarely affected by this condition.
Types of Membranous Nephropathy
Healthcare professionals have divided this condition into 2 categories based on the cause. For example:
- Primary membranous nephropathy (idiopathic) – In such cases, doctors cannot find the exact cause of MN. Approximately 75% of people have this type of MN.
- Secondary membranous nephropathy – It affects 25% of people who develop MN, and it often occurs due to another condition or treatment that negatively affects the kidneys.
Symptoms
While the primary symptom of this condition is excessive protein in the urine caused by kidney damage, MN may cause other symptoms as well. Check some examples below:
- Water retention
- Edema (swelling in the hands or feet due to fluid buildup)
- High cholesterol
- Proteinuria (increased levels of protein in the urine)
- Frequent or reduced urination
- Extreme tiredness (fatigue)
- Hypertension (high blood pressure)
- Dyspnea (shortness of breath)
- Weight gain
If you experience any of the previous symptoms, immediately contact your healthcare professional. Otherwise, it may lead to serious complications (such as permanent damage to the kidneys).
Causes
The primary type of MN is an autoimmune disorder, which means the body mistakenly attacks healthy cells (in such cases, the glomeruli). Usually, the body produces specific antibodies (a protein that helps the body fight infections) called the phospholipase A2 receptor (PLA2R). This antibody begins to attack kidney cells instead of bacteria, viruses, and other germs that can make you ill.
However, some people (about 20% to 25%) may develop MN due to an underlying condition. Check below some health conditions that put you at increased risk of developing MN:
- Autoimmune disorders (such as lupus, rheumatoid arthritis, and others)
- Infections (these include malaria, hepatitis B, hepatitis C, syphilis, and others)
- Cancer (especially colon or lung cancer)
- Some medications – For example, Penicillamine or NSAIDs (nonsteroidal anti-inflammatory drugs)
- Prolonged exposure to mercury and other toxins
What Happens if Membranous Nephropathy is Left Untreated?
People who develop this condition may also experience some complications, especially if the condition is left untreated. Check some of them below:
- High blood pressure
- Severe swelling
- Kidney disease (such as chronic kidney disease or acute kidney injury, which is a medical emergency) or kidney failure
- Deep vein thrombosis (DVT)
- Pulmonary embolism (PE)
- High cholesterol (increased levels of fat in the blood)
- Cardiovascular disease
- Renal tubule damage – This complication occurs due to prolonged protein leakage.
- Blood clots
- Infections
- End-stage renal disease (ESRD)
This document does not contain a full list of MN complications. However, you can consult with your doctor about measures to reduce the risk or prevent the previous complications. In general, there is no way to prevent this condition because it is an autoimmune condition. However, you may take steps to reduce the risk of secondary MN by managing existing health conditions.
Diagnosis
If you experience symptoms that resemble MN, you may be referred to a nephrologist. Therefore, they will perform a physical examination to check for irregularities linked to the disease, and may ask some questions about the symptoms and medical history. In any case, to confirm or exclude, MN doctors often perform the following tests and procedures. For example:
- Blood tests – Doctors often perform these tests to measure kidney function. They often perform blood urea nitrogen (BUN), creatinine, and albumin.
- Glomerular filtration rate (GFR) – This test also involves a blood sample to determine the speed at which your kidneys filter waste.
- Urine test (also known as a urinalysis) – This test helps measure levels of protein and blood in the urine (pee).
- Kidney biopsy – During this test, doctors will take a small sample of a kidney for testing. They often check for antibodies present in people with MN.
Sometimes, doctors may also perform an antinuclear antibody test or an anti-double-stranded DNA test to check for infections or underlying conditions.
Treatment
The treatment goal is to ease the symptoms, prevent life-threatening complications, and improve your quality of life. Check below some options often recommended by doctors to manage MN:
- Angiotensin-converting enzyme (ACE) inhibitors – This group of medicines is used to treat hypertension and inflammation in the kidneys.
- Angiotensin receptor blockers (ARBs) – This group of medicines is often recommended when ACE inhibitors are not an option to treat hypertension and kidney disease.
- Diuretics (also called water pills) – These medicines are used to remove excess water from the body.
- Statins (cholesterol-lowering medicines) – Doctors often recommend these medications to treat high cholesterol.
- Corticosteroids – These medications are used to reduce inflammation and suppress the immune system.
- Blood thinners (also called anticoagulants) – They are used to reduce the risk of blood clots.
- Dietary changes – It is also recommended to reduce salt intake and keep overall protein intake at a moderate level.
When previous treatments do not work, physicians may recommend immunotherapy drugs that suppress the immune system to produce antibodies that attack healthy cells. They often prescribe Rituximab or Cyclophosphamide. In more severe cases, physicians may recommend dialysis or a kidney transplant.
Frequently Asked Questions
Is there a cure for membranous nephropathy?
Unfortunately, there is no way to cure this condition. That’s why the treatment goal is to relieve the symptoms, prevent serious complications, and improve your quality of life.
Is membranous nephropathy fatal?
Usually, this condition is not fatal, but without treatment, the mortality (death) rate significantly increases. Generally, kidney failure happens in about 15% of people who suffer from MN.
What is the most common cause of membranous nephropathy?
Approximately 75% to 80% of people develop this condition for unknown causes. However, secondary membranous nephropathy may occur due to hepatitis B, NSAIDs, systemic lupus erythematosus, cancer, and other infections. If you have any other questions, ask your healthcare professional.
