The U.S. Food and Drug Administration has allowed marketing of the first test that can help determine if a specific type of kidney disease, called membranous glomerulonephritis (MGN), is due to the body's rejection of its own kidney tissue (autoimmune) or if it is due to another cause (such an infection).
Membranous glomerulonephritis (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 to remove 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, high blood pressure and increased predisposition to blood clots. Over time, usually 10-20 years, some people with MGN proceed 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 or tumors, adverse reactions to drugs, or poisoning. However, 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.
The EUROIMMUN Anti- PLA2R IFA blood test detects if a patient has an antibody (a protein molecule the body's immune system produces) that is specific to pMGN.
"Treatment of MGN depends on the underlying cause of the disease," said Alberto Gutierrez, Ph.D., director of the Office of In Vitro Diagnostics and Radiological Health in the Center for Devices and Radiological Health at the FDA. "This test can help patients get a timely diagnosis for their MGN and aid with earlier treatment."
The FDA's review included a clinical study of 560 blood samples of which 275 samples were obtained from patients with presumed pMGN, while 285 samples were obtained from patients diagnosed with other kidney diseases (including secondary MGN) and autoimmune diseases, not including pMGN, that can damage the kidney, like lupus. The test was able to detect pMGN in 77 percent of the presumed pMGN samples, and gave a false positive result in less than 1 percent of the other disease samples. Notably, the test was helpful in distinguishing between pMGN from sMGN 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.
The test should not be used to monitor the stage of disease or the response to treatment.
The FDA reviewed the EUROIMMUN Anti- PLA2R IFA blood test through its de novo classification process, a regulatory pathway for some novel low- to moderate-risk medical devices that are first-of-a-kind.
EUROIMMUN Anti- PLA2R IFA is manufactured by EUROIMMUN US, Inc. in Morris Plains, N.J.