High levels of protein in a patient's urine shortly after an episode of acute kidney injury is associated with increased risk of kidney disease progression, providing a valuable tool in predicting those at highest risk for future loss of kidney function.
This finding, published Jan. 27 in JAMA Internal Medicine by Vanderbilt University Medical Center researchers and collaborators from three other centers in North America, suggests that a greater emphasis should be placed on measuring urine protein levels in patients following acute kidney injury to ensure they receive appropriate follow-up.
Although protein levels in urine are known to rise after acute kidney injury, these protein levels are seldom measured, omitting a key piece of a patient's overall kidney health that is important for proper clinical decision making. Failing to measure urine protein levels also hinders the opportunity to reduce high levels of protein through targeted therapies, which could reduce adverse health outcomes following acute kidney injury.
In this study, researchers analyzed data from more than 1,500 hospitalized adults -- half of whom had acute kidney injury -- who completed an outpatient study visit three months after discharge. Patients were tested for proteinuria -- or high levels of protein in their urine -- and were followed for up to five years to assess for progression of kidney disease.
Disease progression was defined as a 50% decrease in the patient's ability to filter blood through the kidneys or by a diagnosis of end-stage renal disease.
The study found that high levels of protein in urine was a strong discriminator for future kidney disease progression, and when combined with other known risk factors for future loss of kidney function, risk could be better discriminated and predicted.
"Rates of acute kidney injury are growing, along with the number of people who leave the hospital after experiencing it. Some of these people will be at higher risk for future loss of kidney function," said Edward Siew, MD, MSCI, associate professor of Medicine in the Division of Nephrology at VUMC and senior author of the paper.
"As most will be seen by their primary care physicians, these findings inform the broader medical community that including a simple measurement of urine protein levels in the assessment of kidney function in the aftermath of an acute kidney injury episode can help identify those at highest risk, suggest potential strategies to reduce these risks and guide appropriate referrals."