Protecting the kidneys after heart surgery

Following cardiac surgery, many patients experience acute kidney injury (AKI), a complication that increases the risk of mortality. To evaluate kidney function and diagnose AKI, clinicians traditionally measure creatinine levels in a patient’s bloodstream, but it may take up to three days for the concentration of this biomarker to peak.

New research published in two companion articles in the August 11 issue of the Journal of the American Society of Nephrology by a multidisciplinary group of Yale scientists suggests that measuring other biomarkers may be more effective.

The group, led by Chirag Parikh, M.D., Ph.D., associate professor of medicine, collected samples from adult and pediatric patients undergoing cardiac surgery and measured the level of the proteins IL-18 and NGAL in urine, and NGAL in blood. These biomarkers identified AKI within six hours of surgery and one to two days earlier than creatinine. In addition, the IL-18 and plasma NGAL levels identified the adult patients who go on to develop severe kidney injury after cardiac surgery. Of the three biomarkers tested, urine IL-18 levels showed the strongest association (over a six-fold increase in risk) with severe AKI in both adults and children.