In the Journals

Urine biomarkers in postnatal infants associated with acute kidney injury

David J. Askenazi

Urine biomarkers determined in the first four days of life were associated with acute kidney injury during the first postnatal weeks, according to a recent prospective cohort study.

“The field of urine protein biomarkers shows promise of someday being able to diagnose [acute kidney injury (AKI)] early in the disease process by non-invasively measuring specific urine proteins,” David J. Askenazi, MD, MsPH, from the division of pediatric nephrology at the University of Alabama at Birmingham, and colleagues wrote. “Improving the ability to reliably detect AKI would have important implications in the ability to care for critically ill neonates and will also improve the ability to perform clinical research.”

To understand urine kidney damage in premature infants and whether biomarkers could improve detection of kidney damage, researchers assessed the association between 14 urine biomarkers and AKI in 113 very-low birth weight infants (weight ≤ 1,200 g or < 31 weeks’ gestation) admitted between February 2012 and June 2013 to regional neonatal ICU at the University of Alabama at Birmingham.

The researchers measured serum creatinine (SCr) on postnatal days 1, 2, 3 and 4, which they combined with clinically measured SCr to find AKI. They defined AKI as an increase in SCr of 0.3 mg/dL or greater or as a 50% or greater increase from previous lowest value. They gathered urine on the first four days (average urines, 3; range, 1–4). Researchers then calculated the highest urine biomarkers and biomarker/creatinine levels for 12 urine biomarkers and calculated the lowest urine biomarker and biomarker/creatinine levels for two. Then they used these values to compare those with AKI with those without AKI.

Twenty-eight of the 113 infants (25%) had cumulative incidence of AKI during the first two postnatal weeks. Infants with AKI had higher maximum levels of urine cystatin c (2 times higher), neutrophil gelatinase associated lipocalin (1.8 times higher), osteopontin (1.7 times higher), clusterin (1.7 times higher) and alpha glutathione S-transferase (3.7 times higher). They also had lower minimum levels of epithelial growth factor (1.4 times lower) and uromodulin (1.6 times lower) than in those without AKI. Further, most infants had their maximum, or minimum, biomarker values prior to AKI.

“Before we can incorporate urine biomarkers into clinical practice, the scientific community needs to show that candidate biomarkers predict significant clinical outcomes, including the development of chronic kidney disease,” Askenazi and colleagues wrote. “Larger well-designed studies that can stratify patients at risk, determine the etiology of rising SCr, and evaluate clinical outcomes (including CKD) will be needed to help validate the use of urine biomarkers in clinical care.”— by Savannah Demko

Disclosure: The researchers report no relevant financial disclosures.

David J. Askenazi

Urine biomarkers determined in the first four days of life were associated with acute kidney injury during the first postnatal weeks, according to a recent prospective cohort study.

“The field of urine protein biomarkers shows promise of someday being able to diagnose [acute kidney injury (AKI)] early in the disease process by non-invasively measuring specific urine proteins,” David J. Askenazi, MD, MsPH, from the division of pediatric nephrology at the University of Alabama at Birmingham, and colleagues wrote. “Improving the ability to reliably detect AKI would have important implications in the ability to care for critically ill neonates and will also improve the ability to perform clinical research.”

To understand urine kidney damage in premature infants and whether biomarkers could improve detection of kidney damage, researchers assessed the association between 14 urine biomarkers and AKI in 113 very-low birth weight infants (weight ≤ 1,200 g or < 31 weeks’ gestation) admitted between February 2012 and June 2013 to regional neonatal ICU at the University of Alabama at Birmingham.

The researchers measured serum creatinine (SCr) on postnatal days 1, 2, 3 and 4, which they combined with clinically measured SCr to find AKI. They defined AKI as an increase in SCr of 0.3 mg/dL or greater or as a 50% or greater increase from previous lowest value. They gathered urine on the first four days (average urines, 3; range, 1–4). Researchers then calculated the highest urine biomarkers and biomarker/creatinine levels for 12 urine biomarkers and calculated the lowest urine biomarker and biomarker/creatinine levels for two. Then they used these values to compare those with AKI with those without AKI.

Twenty-eight of the 113 infants (25%) had cumulative incidence of AKI during the first two postnatal weeks. Infants with AKI had higher maximum levels of urine cystatin c (2 times higher), neutrophil gelatinase associated lipocalin (1.8 times higher), osteopontin (1.7 times higher), clusterin (1.7 times higher) and alpha glutathione S-transferase (3.7 times higher). They also had lower minimum levels of epithelial growth factor (1.4 times lower) and uromodulin (1.6 times lower) than in those without AKI. Further, most infants had their maximum, or minimum, biomarker values prior to AKI.

“Before we can incorporate urine biomarkers into clinical practice, the scientific community needs to show that candidate biomarkers predict significant clinical outcomes, including the development of chronic kidney disease,” Askenazi and colleagues wrote. “Larger well-designed studies that can stratify patients at risk, determine the etiology of rising SCr, and evaluate clinical outcomes (including CKD) will be needed to help validate the use of urine biomarkers in clinical care.”— by Savannah Demko

Disclosure: The researchers report no relevant financial disclosures.