WEDNESDAY, Jan. 21 (HealthDay News) -- A new urine test that can detect a common cause of kidney transplant failure may help lead to better diagnosis and treatment of patients with polyomavirus nephropathy, which affects about 9 percent of kidney transplant patients.

Polyomaviruses are harmless to healthy adults but can cause serious problems for people with compromised immune systems. People having a kidney transplant take medicines to suppress their immune system to protect against organ rejection.

There are no effective treatments for polyomavirus nephropathy, so it's important to diagnose the condition as soon as possible and lower the dose of immunosuppressive drugs in hopes of allowing the immune system to eliminate the virus. Currently, doctors rely on invasive and expensive kidney biopsies to diagnose polyomavirus nephropathy, and these tests sometimes give false negative results.

The new test -- developed by Dr. Volker Nickeleit and colleagues from the University of North Carolina at Chapel Hill -- measures levels of Haufen,, a German word for the tightly clustered viral aggregates that form in the kidneys of people with polyomavirus nephropathy and are excreted in the urine.

The researchers said the test takes three hours, costs less than $400, and is easy to perform with existing laboratory equipment. When the test was used on 160 people, including 21 with early- or late-stage polyomavirus nephropathy, the researchers detected Haufen in urine samples from all 21 people with the virus but in none of the 139 study participants without the condition.

The study was published in the February issue of the Journal of the American Society of Nephrology.

"An early and accurate diagnosis of polyomavirus nephropathy will result in a better understanding of the disease and ultimately improve treatment," Nickeleit said in an American Society of Nephrology news release. "Our diagnostic test is unique and could have a tremendous clinical impact."

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