The wave of the future: Noninvasive tests for kidney transplants
By Darla Ferrara

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Kidney transplants enhance the quality of life for patients with chronic or end-stage renal disease. It is the modality of choice for individuals battling diabetic nephropathy and for pedantic renal patients. Rejection is always a consideration when discussing the success rate of solid organ transplants. A recent study by the National Institute of Allergy and Infectious Diseases offers a noninvasive way to provide early indication of rejection.


Will this new protein test be more effective than a biopsy?
  • 1. Yes
  • 2. No

The study suggests that low levels of the CXCL9 protein are an indicator of how likely rejection is after transplant surgery. The results, published in the American Journal of Transplantation, show that adding this basic urine test to post surgical evaluations will enable doctors to pinpoint patients entering the rejection cycle, especially in the first year when 10 to 15 percent of rejections occur.

Currently, the only way to tell the difference between rejection and other types of post-transplant kidney injury is through biopsy. Although this minor surgical procedure puts the patient at little risk, it is not an accurate representation of overall kidney health. NIAID Director Anthony Fauci, M.D. points out that using a noninvasive urine test could all but eliminate the need for biopsies. The goal is to allow doctors to gauge the requirement for immunosuppressive therapy, which comes with its own set of risks.

The Clinical Trials in Organ Transplantation study collected samples from 280 adults and children who had gone through a kidney transplant. The researchers, Peter Heeger, M.D., from Icahn School of Medicine and Donald Hricik, M.D., from Case Western Reserve University, measured their urine for molecules often found in rejection looking for biomarkers. The search included two proteins and nine mRNAs.

The conclusion was that the CXCL9 protein and CXCL9 mRNA serve as accurate gauges for potential rejection. Low levels indicate little to no immune response to the new organ. In other words, the presence of these two biomarkers in urine helps to determine the likelihood of organ rejection.

Further testing narrowed down the search even more effectively. The study shows the CXCL9 protein offers a more accurate view of rejection possibility. It produced a positive predictive value of 67.6 percent and a negative predictive value of 92 percent (a lower number is more telling than higher one).

Tranplant recipients who maintain low levels of this protein in their urine six months post-transplant have increased chance of stable long-term kidney function. The test helps classify patients least likely to develop future AR or have a decrement in glomerular filtration rate between six and 24 months.

What does this mean to the transplant community? The ability to wean patients off immunosuppressant drugs early will reduce side effects such as infection and uncontrolled bleeding. It also reduces problems that can further wear down the body's resistance such as loss of appetite and chronic vomiting.

The development of a noninvasive test to determine immune activation means doctors have something more conclusive to work with than a biopsy when determining the health of the donated organ. This will cut back of unnecessary surgical procedures and reduce the need for excess preventative immunosuppressant drug therapy. Using biomarkers to assess immune risk will guide therapeutic decision-making in the future.

Darla Ferrara is a freelance writer published internationally and an award-winning author. Publishing credits include USARiseUP, New York Times, AOL and LiveStrong. Ferrara studied biology at the University of Nebraska and emergency medical technology at Southeast Community College.