Membranous Glomerulonephritis

Symptoms develop gradually, and often go unnoticed in the beginning. Severe symptoms usually only occur when kidney disease is advanced.

Signs and symptoms include:

• Swelling in the legs and ankles and other parts of the body (known medically as edema)
• Weight gain
• Fatigue
• Poor appetite
• Trouble sleeping
• Increased urination, especially at night
• Blood clots
• Infections
• Frothy (foamy) urine

MGN is caused by the thickening of part of the glomerular basement membrane, the part of the kidneys that helps filter waste and extra fluid from the blood. The exact reason for this thickening is not known.

The thicker glomerular membrane does not work normally. Large amounts of protein are lost in the urine as a result.

The following increase your risk for this condition:

• Certain autoimmune disorders (when the immune system mistakes some of your own tissues as foreign invaders and attacks them with autoantibodies) such as systemic lupus erythematosus (SLE), rheumatoid arthritis, Graves' disease, and other autoimmune disorders
• Cancers, especially lung and colon cancer, and lymphomas
• Exposure to gold salts and mercury and other toxins or poisons
• Infections, including hepatitis B and C, malaria, syphilis, and endocarditis
• Adverse reactions to certain medications
• Race and age (MGN affects mostly adult, Caucasian men)

About 85 percent of MGN cases are caused by the body’s immune system mistakenly attacking healthy kidney tissue, a condition called primary MGN (pMGN), which is one of the leading causes of kidney disease in adults.

Swelling (edema) is often found during physical exams.

Your healthcare provider may recommend a test called a urinalysis to check for large amounts of protein in your urine. 

Other tests may be done to see how well the kidneys are working and how the body is adapting to the kidney problem. These include:

• Albumin - blood and urine
• Blood Urea Nitrogen (BUN)
• Creatinine - blood
• Creatinine clearance
• Lipid panel
• Protein - blood and urine

A kidney biopsy confirms the diagnosis.

The following tests can help determine the cause of membranous nephropathy:

• Antinuclear antibodies test
• Anti-double-strand DNA, if the antinuclear antibodies test is positive
• Blood tests to check for hepatitis B, hepatitis C, and syphilis
• Complement levels
• Cryoglobulin test

Treatment is aimed at reducing symptoms and slowing the progression of the disease.

Controlling blood pressure is the most important way to delay kidney damage. The goal is to keep blood pressure at or below 130/80 mmHg. Medications prescribed to lower blood pressure include:

• Angiotensin-converting enzyme (ACE) inhibitors 
• Angiotensin receptor blockers (ARBs)

Other treatments are aimed at controlling complications and include:

• Blood levels of cholesterol and triglycerides are often high in people with membranous nephropathy, which greatly increases their risk of heart disease. Medications to reduce cholesterol and triglycerides levels (most often statins) may be recommended.
• Loss of protein from the blood into the urine (proteinuria) in people with membranous nephropathy includes loss of proteins that help prevent clotting. So you are at an increased risk of having blood clots. Patients are occasionally prescribed blood thinners to prevent these complications.
• The buildup of wastes in your bloodstream (uremia) and salt retention can raise your blood pressure.
• You are at increased risk of infections because you lose proteins in the urine that protect you from infection.
• Nephrotic syndrome is a group of signs and symptoms that may accompany conditions that affect the filtering ability of the glomeruli. Nephrotic syndrome is characterized by high protein levels in the urine, low protein levels in the blood, high blood cholesterol, and swelling (edema) of the eyelids, feet and abdomen.
• Acute kidney failure occurs in severe cases of damage to the glomeruli. When this happens, waste products may build up quickly in your blood. You may need emergency dialysis to remove extra fluids and waste from your blood.
• With chronic kidney failure, your kidneys may gradually lose their function over time to the point where you may require dialysis or a kidney transplant. Vitamin D may need to be replaced if nephrotic syndrome is chronic and does not respond to therapy.

The prognosis depends upon the amount of protein that is lost. Some patients have only occasional flare-ups and then go symptom-free for a while. 

MGN may go away with or without treatment. However, most patients will have some kidney damage within 2-20 years. About 20% of those patients will progress to end-stage renal disease.

Over time, usually 10-20 years, some people with MGN proceed to kidney failure and require a kidney transplant.