Tubular damage biomarkers linked to inflammation or iron metabolism predict acute kidney injury

Introduction

Here, we compare the value of acute tubular damage markers measured early in the course after cardiac surgery for prediction of postoperative AKI compared with conventional markers used in clinical routine for risk assessment of acute renal function loss.

Methods

One hundred adult patients undergoing cardiac surgery in the control arm of a RCT (NCT00672334) were analyzed. We quantified the following biomarkers in urine: NGAL, hepcidin, midkine, IL-6, α₁-microglobulin; in plasma: NGAL, hepcidin, haptoglobin, CK, CKMB, CRP, leukocytes, lactate, urea and creatinine.

Results

Preoperatively, no biomarker predicted AKI. At ICU arrival, four urinary tubular damage markers showed good discriminatory ability (AUC ≥0.80) for subsequent development or absence of AKI (Figure 1). An excellent predictive value was found for uNGAL/uhepcidin ratio (AUC 0.90, Figure 1). This ratio combines an AKI prediction marker (NGAL) and a marker of protection from AKI (hepcidin), potentiating their individual discriminatory values. Contrarily, at ICU admission, none of the plasma biomarkers was a good early AKI predictor with AUC-ROC ≥0.80.

Figure 1

(abstract P414)

Conclusion

Several urinary markers of acute tubular damage predict AKI after cardiac surgery and the biologically plausible combination of NGAL and hepcidin provides excellent AKI prediction.