Uric Acid Predicts AKI Risk After Cardiac Surgery

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Serum uric acid levels above the median prior to cardiac surgery is independently associated with 5.5-fold increased odds of postoperative acute kidney injury.
Serum uric acid levels above the median prior to cardiac surgery is independently associated with 5.5-fold increased odds of postoperative acute kidney injury.

Elevated serum uric acid (SUA) levels before cardiac surgery independently predicts an increased risk of postoperative acute kidney injury (AKI), new study findings suggest.

In a study of 247 patients who underwent elective coronary artery bypass grafting, valve replacement/repair or combined bypass and valve surgery, patients with SUA levels above the median (373 µmol/L or higher) had significant 5.5-fold increased odds of AKI compared with those with SUA levels below the median, after adjusting for body mass index, preoperative serum creatinine, diabetes, preoperative diuretic use, and other variables.

In a paper published in BMC Nephrology (2018;19:161). Tim Kaufeld, MD, of Hannover Medical School in Hannover, Germany, and colleagues noted that hyperuricemia could lead to AKI by 2 pathways. Chronically, high uric acid may induce subtle renal damage that predisposes to AKI, which may not be detected preoperatively by serum creatinine, they explained. Acutely, the effect of intraoperative renal hypoperfusion may be aggravated by the pro-inflammatory and pro-oxidative properties of SUA, according to the investigators.

Dr Kaufeld's team concluded that their data indicate that measuring SUA may contribute to preoperative risk assessment.

Of the 247 patients, 124 had preoperative SUA levels above the median and 123 had levels below the median. The mean SUA levels were 464.94 and 301.93 µmol/L, respectively.

Reference

Kaufeld T, Foerster KA, Schilling T, et al. Preoperative serum uric acid predicts incident acute kidney injury following cardiac surgery. BMC Nephrol. 2018;19:161.

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