Simple test spots risk from acute kidney injury

Furosemide

The new test can spot high risk and improve care for patients with acute kidney injury

A simple test used early in the setting of critical illness can help doctors predict which patients with acute kidney injury—which often follows major surgery or severe infection—are most likely to develop serious kidney problems, require dialysis, or die in the hospital.

According to a study published February 5, 2015, in the Journal of the American Society of Nephrology, the furosemide stress test (FST), an established medicine used in a novel, protocolized way, could help clinicians better estimate the risk of adverse patient outcomes with respect to kidney damage.

Jay Koyner, MD

Jay Koyner, MD

“As a functional measure of acute kidney injury, the furosemide stress test was superior to a panel of eight of the most widely investigated biochemical markers of kidney injury,” said Jay Koyner, MD, assistant professor of medicine and medical director of acute dialysis at the University of Chicago Medicine, and lead author of the study. “Use of this test in early AKI could alter patient care and improve clinical decision making.

Acute kidney injury (AKI) is an abrupt decline in kidney function. It is largely asymptomatic, lacking warning signs such as pain, shortness of breath or other clinical symptoms, particularly in the early stages when intervention is likely to be most beneficial. Yet up to 50 percent of critically ill patients develop some degree of AKI during their illness, increasing the risk of dying in the hospital.

Furosemide, a diuretic, marketed as Lasix®, helps the kidneys get rid of excess fluid in the body. It was originally approved for patients with congestive heart failure and edema, but it can also be used to help control blood pressure.

In a study of 77 patients with early AKI, a team led by Koyner and colleague Lakhmir Chawla, MD, associate professor of anesthesiology and critical care medicine and of medicine at George Washington University and Veteran Affairs Medical Center, Washington, DC, found that this simple test, performed with a one-time dose of this FDA-approved medication plus careful measurement of urine output, could effectively make this early diagnostic determination.

“These findings may pave the way to robust clinical diagnostic tools for clinicians who care for patients with AKI,” said Chawla. “In this standardized protocol, we were able to determine which patients may or may not require dialysis for acute kidney injury one to three days ahead of time.”

Using the FST to assess the severity of AKI is similar to the model used in patients with cardiac angina, or chest pain, say the study’s authors. In the cardiac test, a marker such as troponin is used in conjunction with an exercise stress test. Similarly, when FST was used in conjunction with AKI markers, it improved predictions of outcomes in patients with early AKI.

In an accompanying editorial, T. Clark Powell, MPH and David Warnock, MD, of the University of Alabama at Birmingham, note that an important strength of FST is that it “can be performed outside of a critical care unit,” but they also point out that the study’s findings “need to be confirmed and broadened to include more study sites and a larger numbers of individuals.”

“It will be important to see if the predictive power of the FST remains informative for patients who are not in the critical care setting,” they added.

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