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.