The First Roadmap for Laboratory Investigation of Acute Kidney Injury

Detecting acute kidney injury (AKI) continues to challenge both clinicians and laboratorians. Even after standardization efforts for the traditional marker creatinine, a large gap remains in our ability to quickly detect AKI and meaningfully improve outcomes.

A new AACC Academy guidance document seeks to close this gap and provide the first up-to-date evidence-based recommendations for laboratory evaluation of AKI. The scientific session on Tuesday, December 15 at 2:00 pm Central, “Laboratory Investigation of Acute Kidney Injury: Highlights from the New AACC Academy Guidance Document” brings together three speakers to help attendees digest this new roadmap for both clinicians and laboratorians.

Melanie Hoenig, MD, explores the guidance document through the lens of a practicing nephrologist by describing laboratory evaluations performed during the workup of AKI and detailing which members of the care team order each test. Collaboration between laboratories and nephrology services will become increasing important to properly identify and treat AKI early. The conventional laboratory tests for AKI such as urine sediment, serum and urine sodium, serum and urine creatinine, and urine output remain at the forefront for diagnosis.

“The new biomarkers are not ready for prime time and cystatin C is only available on limited platforms,” says Hoenig. The new markers are only going to complicate the landscape so now is the time to make best practice recommendations and establish a baseline for care, she adds.

Speaker Joe El-Khoury, PhD, covers the analytical performance of and established clinical utility for existing and emerging biomarkers of AKI. The Holy Grail for detecting AKI early would be discovery of a kidney troponin biomarker similar to the rise in cardiac troponin exquisitely associated with myocardial injury. El-Khoury says our current ability to detect AKI with creatinine is poor because we don’t detect a change until 24-48 hours after injury. He explains that the new guidance document evaluated the very definition of AKI and discovered that the current definition from Kidney Disease: Improving Global Outcomes is not supported by evidence from biological or analytical variability.

He shares that the new recommended definition for a significant change is 0.20 mg/dL if creatinine <1.00 mg/dL or 20% if creatinine is >1.00 mg/dL. “This reference change value is an evidence-based recommendation that laboratorians can help implement into clinical practice,” says El-Khoury. Defining what constitutes a real change for creatinine is just one of many elements that attendees will come away with from this session.

Nichole Tolan, PhD, focuses on implementing these guidelines through automated identification and laboratory alerts. To start, Tolan brings everything back to assay performance. Understanding an assay’s analytical variation is key to defining a clinically significant change for a lab, she states. “It’s really important to know your creatinine assay and ensure you maintain those original performance specifications.”

Tolan emphasizes that a recommended reference change value might not be appropriate for an assay with a poor precision profile, adding that labs should carefully implement automated alerts in collaboration with their colleagues. Primary care providers and nephrologists might want to know additional information about changes in creatinine lab results, but it’s important to be prepared for the consequences.

AACC Academy’s new guidance document provides evidence-based support for an unmet need. Attendees will leave today’s session with a better understanding of these new recommendations and the tools to implement them in clinical practice.