HOUSTON—Researchers have identified two novel biomarkers that improve clinicians’ ability to predict acute kidney injury (AKI) in patients following cardiac surgery.

The biomarkers, neutrophil gelatinase-associated lipocalin (NGAL) and cystatin C, were superior to conventional biomarkers (creatinine and urea), lead investigator Michael Haase, MD, of Charité University Medicine in Berlin, reported here at the 29th Annual Dialysis Conference.

He and his colleagues, prospectively studied 100 adult cardiac surgery patients. They measured serum concentrations of NGAL, cystatin C, creatinine, and urea at baseline, on arrival in the intensive care unit (ICU), and 24-hours postoperatively.

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They evaluated the biomarkers in relation to the development of AKI, defined as a greater than 50% increase in serum creatinine and to a composite end point (need for renal replacement therapy and in-hospital mortality). AKI developed in 23 patients.

On arrival in the ICU, serum NGAL and cystatin C were significantly better than creatinine and urea at predicting AKI, Dr. Haase told listeners. Each biomarker predicted 75% of the AKI cases. When used together, the biomarkers predicted 80% to 85% of cases, Dr. Haase said.

By comparison, serum creatinine and urea predicted 60% and 55% of cases, respectively. NGAL predicted AKI 48 hours before serum creatinine.

At 24 hours postoperatively, all four biomarkers had good predictive value, he said.

NGAL and cystatin C were independent predictors of AKI and of “excellent value” in predicting the composite end point, the researchers concluded.

Study findings were published recently in Critical Care Medicine (2009;37:553-560).