Marker for Acute Kidney Injury Proves Reliable in Emergency Room Setting

AKI is associated with deterioration of renal function that may be discovered by a measured decrease in urine output. Often, it is diagnosed based on blood tests for substances normally eliminated by the kidney: urea and creatinine. However, both these tests have disadvantages. For instance, it takes about 24 hours for the creatinine level to rise, even if both kidneys have ceased to function.

In contrast, NGAL is secreted in high levels into the blood and urine within two hours of AKI. Since NGAL is protease resistant and small, the protein is easily excreted and detected in the urine. NGAL levels in patients with AKI have been associated with the severity of their prognosis and can be used as a biomarker for AKI.

In a prospective cohort study, 616 patients admitted from the emergency department of Fernando Fonseca Hospital (Lisbon, Portugal from March to November 2008 were classified according to clinical criteria for AKI, kidney trauma, or normal function. NGAL was measured serially. Investigators at Cincinnati Children's Hospital Medical Center (Ohio, USA) evaluated the findings.

Results showed that 21% of patients were classified as AKI, and the highest median levels of plasma NGAL were in the AKI group. NGAL levels discriminated AKI from normal function and transient kidney dysfunctions. Patients were classified into three grades of AKI risk according to NGAL levels (low, moderate, and high). Patients with plasma NGAL in the high-risk category displayed a 10-fold greater risk of AKI.

"The majority of our studies on NGAL have been performed in well controlled settings of hospital-acquired AKI, such as cardiac surgery, contrast administration, or other critically ill patients," said senior author Dr. Prasad Devarajan, director of nephrology and hypertension at Cincinnati Children's Hospital Medical Center. "The purpose of this study was to determine the biomarker's accuracy in a diverse group of patients admitted from the emergency department, where patients with early signs of AKI are often misdiagnosed."

"This latest study showed that this simple laboratory test provides an accurate prediction of acute kidney injury and its severity in a diverse clinical setting," said Dr. Devarajan. "The identification of biomarkers that differentiate intrinsic AKI from transient reversible forms of renal dysfunction and predict outcomes is a high priority."

The study was published in the September 5, 2013, online edition of the Clinical Journal of the American Society of Nephrology.

Related Links:
Fernando Fonseca Hospital
Cincinnati Children's Hospital Medical Center