Biomarkers Predict Kidney Problems After Cardiac Surgery

Blood and urine markers can indicate which patients with an abrupt kidney injury following heart surgery will experience progressive kidney problems.

Until now, doctors have not been able to determine which cases of acute kidney injury (AKI) that develop after heart surgery will worsen so testing for these markers soon after surgery could help doctors protect the health of patients' kidneys.

At Yale University School of Medicine (New Haven, CT, USA) investigators found that the presence of certain markers on the day that AKI is diagnosed can indicate structural injury to the kidneys that will likely cause patients to experience progressive problems. They prospectively enrolled 1,219 adults undergoing cardiac surgery (coronary artery bypass grafting or valve surgery) who were at high risk for AKI at six academic medical centers in North America between July of 2007 and December of 2009. Urine and plasma specimens collected preoperatively and daily for up to five postoperative days.

High urinary interleukin-18 (IL-18) and the albumin-to-creatinine ratio (ACR) increased patients' risk of experiencing persistent AKI by approximately three-fold, while high blood levels of a protein called neutrophil gelatinase-associated lipocalin (NGAL) increased their risk by more than seven-fold. Urine IL-18 and NGAL were measured with the ARCHITECT assay (Abbott Diagnostics, Abbott Park, IL, USA). Plasma NGAL was measured through the Triage NGAL immunoassay in conjunction with the TriageMeter (Biosite Inc., San Diego, CA, USA).

The authors concluded that urinary IL-18, ACR, and plasma NGAL measurement at the time of clinical creatinine increase forecasted the progression of AKI in adults after cardiac surgery. Chirag Parikh, MD, PhD, a lead author of the study said, "Our multicenter study is the largest acute kidney injury biomarker study performed to date in adults, and it strengthens the new paradigm that assessing structural injury at the time of clinical diagnosis with urine or blood markers of kidney injury can yield important prognostic information." The study was published online on March 1, 2012, in the Journal of the American Society Nephrology.

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Yale University School of Medicine
Abbott Diagnostics
Biosite Inc