FDA Approves First Non-Invasive Test to Help Identify Cause of Kidney Disease
Blood test targets membranous glomerulonephritis
The FDA has allowed marketing of the first test that can help determine whether a specific type of kidney disease — membranous glomerulonephritis (MGN) — is due to the body’s rejection of its own kidney tissue (autoimmune) or whether it is due to another cause, such as infection.
MGN is a chronic kidney disease that causes damage to the cluster of blood vessels (glomeruli) in the kidney that filter the blood and begin the process of removing waste and excess fluid from the blood. Once the disease progresses, other areas of the kidney become damaged. Symptoms of MGN include swelling, high cholesterol, hypertension, and increased predisposition to blood clots. Over time (usually 10 to 20 years), some people with MGN progress to kidney failure and require a kidney transplant. MGN affects mostly adult, Caucasian men.
Some cases of MGN are associated with secondary conditions, such as infections, tumors, adverse reactions to drugs, or poisoning. However, approximately 85% of cases of MGN are caused by the body’s immune system attacking healthy kidney tissue, a condition called primary MGN (pMGN), which is one of the leading causes of kidney disease in adults.
The Euroimmune Anti-PLA2R IFA blood test (Euroimmune US, Inc.) detects whether a patient has an antibody that is specific to pMGN.
The FDA’s review included a clinical study of 560 blood samples. Of these samples, 275 were obtained from patients with presumed pMGN, and 285 were obtained from patients diagnosed with other kidney diseases (including secondary MGN) and autoimmune diseases (excluding pMGN) that can damage the kidney, such as lupus. The blood test was able to detect pMGN in 77% of the presumed pMGN samples, and gave a false positive result in less than 1% of the other disease samples. Notably, the test was helpful in distinguishing pMGN from secondary MGN in most of the patients.
The test should not be used alone to diagnose pMGN. Additional information, including patient symptoms and other laboratory tests, should always be considered when making a diagnosis of pMGN. A biopsy of the kidney is needed to confirm the diagnosis of pMGN. A negative result from the test does not rule out a diagnosis of pMGN.
Moreover, the test should not be used to monitor the stage of kidney disease or the patient’s response to treatment.
Source: FDA; May 29, 2014.