FDA Clears Noninvasive Kidney Disease Test for Marketing

Troy Brown, RN

Disclosures

May 30, 2014

The US Food and Drug Administration (FDA) has allowed marketing of the first noninvasive test for determining the cause of membranous glomerulonephritis (MGN). The test (EUROIMMUN Anti-PLA2R IFA, EUROIMMUN US, Inc) will help determine whether the cause is autoimmune or whether it results from another cause, such as infection.

MGN is a chronic disease that damages the glomeruli in the kidney. As the disease progresses, damage spreads to other parts of the kidney. Symptoms include swelling, high cholesterol, hypertension, and increased tendency to develop blood clots. Over the course of about 10 to 20 years, some patients develop kidney failure and require a kidney transplant. The disease affects primarily adult, white men. According to the National Institutes of Health, the disorder occurs in about 2 of every 10,000 people.

Some cases are caused by secondary conditions including infections or tumors, adverse drug reactions, or poisoning (sMGN). Most cases — about 85% — are caused by the body's immune system mistakenly attacking its own healthy kidney tissue. This condition is known as primary MGN (pMGN) and is 1 of the leading causes of kidney disease in adults.

The new blood test determines whether or not the patient has an antibody specific to pMGN.

"Treatment of MGN depends on the underlying cause of the disease," Alberto Gutierrez, PhD, director of the Office of In Vitro Diagnostics and Radiological Health in the Center for Devices and Radiological Health at the FDA said in a statement. "This test can help patients get a timely diagnosis for their MGN and aid with earlier treatment."

The decision follows a review of a clinical study of 560 blood samples, 275 of which were obtained from patients thought to have pMGN and 285 of which were from patients diagnosed with other kidney diseases including secondary MGN and autoimmune diseases (not pMGN) that can damage the kidney, such as lupus. The test detected pMGN in 77% of presumed pMGN samples and was falsely positive in less than 1% of the other disease samples. The test helped distinguish between pMGN and sMGN in most of the samples tested.

The test is not intended to be used alone to diagnose pMGN. The clinician should consider additional information, including patient symptoms and other laboratory tests, when making a diagnosis of pMGN. A negative test result does not rule out pMGN, and a kidney biopsy is needed to confirm the disease. The test is not intended for monitoring stage of disease or the response to treatment.

The FDA reviewed the test through its de novo classification process, a regulatory pathway for certain novel low- to moderate-risk medical devices that are the first of their kind.

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