New Test Helps Predict Acute Kidney Injury in ICU Patients

A new study describes a laboratory test for urine neutrophil gelatinase–associated lipocalin (uNGAL), which could possibly help predict whether patients in intensive care units (ICUs) will develop acute kidney injury (AKI).

Researchers at Vanderbilt University Medical Center (Nashville, TN, USA) prospectively evaluated a heterogeneous population of 451 critically ill ICU adult patients, of whom 64 (14%) developed AKI within 24 hours of enrollment and 86 (19%) developed AKI within 48 hours of enrollment. The researchers found that compared with those who did not develop AKI those who did had higher median uNGAL at enrollment. The increase in uNGAL in patients who later developed AKI occurred before any change in serum creatinine (SCr) level, which is typically used to diagnose AKI. After adjustment for age, SCr level closest to enrollment, illness severity, sepsis, and ICU location, uNGAL remained independently associated with the development of AKI. However, the researchers cautioned that adjusted uNGAL only marginally improved the predictive performance of the clinical model alone. The study was published in the August 2009 issue of the Journal of the American Society of Nephrology.

"Although a single measurement of [urine NGAL] exhibited moderate predictive utility for the development and severity of AKI in a heterogeneous ICU population, its additional contribution to conventional clinical risk predictors appears limited,” conclude lead author T. Alp Ikizler, M.D., and colleagues of the division of nephrology.
"The role of urine NGAL in predicting more important measures of AKI severity, including dialysis provision or mortality, remains to be fully explored in larger cohorts.”

NGAL, a ubiquitous 25-kDa protein, is generally expressed in low concentrations, but it increases greatly in the presence of epithelial injury and inflammation. A significant rise in uNGAL 2 days before the rise in SCr was observed in children with AKI following cardiopulmonary bypass (CPB). Adults who developed AKI after cardiac surgery also had significantly elevated levels by one to three hours after the operation. Other human studies demonstrated a strong relationship between uNGAL and AKI in renal transplantation, diarrhea-associated hemolytic-uremic syndrome, and lupus nephritis.

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Vanderbilt University Medical Center