Hope for Easier Transplant Tests

Kidney transplant rejection could be predicted with urine tests

Even after a kidney disease patient gets a long-awaited kidney transplant, the battle isn't over yet. The patient has to be closely watched to make sure the body accepts the new organ. New research suggests that less invasive tests for kidney rejection may soon be an option.

Researchers recently reviewed urine samples from kidney transplant patients to look for signs of kidney failure. They compared the urine samples of successful transplants to those of failed transplants.

These researchers found that low levels of certain particles in urine can show if a body is accepting a kidney transplant. Previously, doctors have had to examine a small sample of the kidney to see if the body was rejecting it.

This research could result in easier, less painful tests for kidney transplant patients.

"Ask a nephrologist about less invasive tests after kidney transplantation."

Manikkam Suthanthiran, MD, and colleagues conducted this research, which aimed to find a less invasive way to see if a patient's body might reject a kidney transplant.

Transplant rejection occurs when a body's immune system reacts against the newly transplanted tissue. The immune system destroys the new organ, often putting the patient's life at risk.

The risk of kidney rejection can be lessened when the donor's tissue is similar to the recipient's and when the recipient's immune system is suppressed.

But even when patients receive therapy to prevent the immune system from rejecting the organ, 10 to 15 percent of patients still experience transplant rejection.

Kidney transplant recipients who show signs of rejection normally undergo a biopsy, in which a doctor removes kidney tissue and examines it. However, this procedure can be painful and is not always accurate.

“Potentially, a noninvasive test for rejection would allow physicians to more accurately and routinely monitor kidney transplant recipients,” said Daniel Rotrosen, MD, of the National Institute of Allergy and Infectious Diseases.

To find other predictors for organ rejection, the researchers gathered 4,300 urine samples from 485 kidney transplant recipients. The samples were taken between three days and one year after the transplant.

The researchers examined the urine samples for biomarkers, or molecules, that indicate a possible organ rejection. They found that a group of three molecules frequently appeared in the urine of patients who experienced a transplant rejection.

They found high amounts of the molecules that predicted a transplant rejection in the 20 days before a biopsy confirmed a rejection.

For patients who had a successful kidney transplant, the amount of rejection biomarkers remained constant and low.

The study authors concluded that their findings may be helpful in developing a urine test for kidney transplant rejection, similar in kind to a pregnancy test.

Such a test would reduce the need for a patient to undergo a biopsy. However, some physicians might encourage patients with positive urine tests to undergo a biopsy to double check.

According to Nancy Bridges, MD, who co-authored this study, "The test described in this study may lead to better, more personalized care for kidney transplant recipients by reducing the need for biopsies and enabling physicians to tailor immunosuppressive therapy to individual patients."

This study was published July 4 in The New England Journal of Medicine.

The research was funded by the National Institute of Allergy and Infectious Diseases, the National Institutes of Health, the National Center for Advancing Translational Sciences and the Qatar National Research Fund.

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Review Date: 
July 24, 2013