AACC Guidance Document on Laboratory Investigation of Acute Kidney Injury

Abstract

Background Acute kidney injury (AKI) is a sudden episode of kidney damage or failure affecting up to 15% of hospitalized patients and is associated with serious short- and long-term complications, mortality, and health care costs. Current practices to diagnose and stage AKI are variable and do not factor in our improved understanding of the biological and analytical variability of creatinine. In addition, the emergence of biomarkers, for example, cystatin C, insulin-like growth factor binding protein 7, and tissue inhibitor of metalloproteinases 2, and electronic notification tools for earlier detection of AKI, highlights the need for updated recommendations to address these developments. Content This AACC Academy guidance document is intended to provide laboratorians and clinicians up-to-date information regarding current best practices for the laboratory investigation of AKI. Topics covered include: clinical indications for further investigating potential AKI, analytical considerations for creatinine assays, the impact of biological variability on diagnostic thresholds, defining “baseline” creatinine, role of traditional markers (urine sodium, fractional excretion of sodium, fractional excretion of urea, and blood urea-to-creatinine ratio), urinary microscopic examination, new biomarkers, improving AKI-associated test utilization, and the utility of automated AKI alerts. Summary The previous decade brought us a significant number of new studies characterizing the performance of existing and new biomarkers, as well as potential new tools for early detection and notification of AKI. This guidance document is intended to inform clinicians and laboratorians on the best practices for the laboratory investigation of AKI, based on expert recommendations where the preponderance of evidence is available.

Complementary methods for SARS-CoV-2 diagnosis in times of material shortage

“…In all RT-qPCR assays either detecting hRNase P, which served as an endogenous control for sample integrity and proper RNA extraction, Ct values obtained for samples taken by Q-tips were similar to those obtained by rayon swab 10 , while samples taken by flocked swab showed fewer copies. As recommended, flocked swabs are stored in 2 ml of saline after sampling and only 1/14 of the volume is used in the subsequent RT-qPCR assay.…”

Changing serum creatinine in the detection of acute renal failure and recovery following radiocontrast studies among acutely ill inpatients: Reviewing insights regarding renal functional reserve gained by large-data analysis

“…1 , with a sharp rise in SCr at the lower range or renal function, our estimates regarding AKI and AKR, based on KDIGO criteria, might be somewhat skewed, amplifying projected changes in eGFR at the range of advanced renal dysfunction. Noteworthy, a new AACC Academy definition of AKI [ 31 ], based on biological variability data with strong clinical outcomes, states that a change of 20% should be more appropriate for the definition of AKI/AKR at SCr levels ≥1 mg/dL, whereas a change of ≥0.2 mg/dL should be used when SCr is < 1 mg/dL. This could prevent a substantial overestimation of AKI/AKR in patients with advanced CKD [ 32 ], questioning our conclusions regarding the 1.55 folds increase in the risk to develop AKI following radiocontrast-enhanced CT among patients with eGFR< 30 ml/min/1.73 m 2 .…”

Biomarker Rule-in or Rule-out in Patients With Acute Diseases for Validation of Acute Kidney Injury in the Emergency Department (BRAVA): A Multicenter Study Evaluating Urinary TIMP-2/IGFBP7

“…The current KDIGO definition may increase diagnostic false-positives in patients with stable CKD because of inherent laboratory and biological variabilities of sCr [ 32 ]. A new recommendation is to use a 20% change to define AKI when the sCr value is >1 mg/dL, and it has been independently correlated with mortality [ 33 , 34 ]. In all AKI patients in the CKD group (13/95 patients, 22%), the sCr change (median, 42.3%) fulfilled this new recommendation.…”