Novel biomarkers in acute kidney injury
Pavai Sthanehwar
Department of Pathology, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur
The National Institutes of Health (NIH) Biomarkers Definitions Working Group has defined a biomarker as, “a characteristic that is objectively measured and evaluated as an indicator of normal biologic processes, pathogenic processes, or pharmacologic responses to a therapeutic intervention." Acute kidney injury (AKI) is common among acutely ill patients and it is associated with high morbidity, mortality, prolonged hospitalization. Currently, the standard diagnostic tools for AKI detection are monitoring of serum creatinine concentration and urine output. However, it is known that these classical markers are not useful for the early diagnoses of AKI. Within the past two decades, a few novel potential biomarkers that are measurable in urine or plasma of patients with AKI have been identified. Recent advances in molecular biology have resulted in promising biomarkers for AKI diagnosis, including neutrophil gelatinase associated lipocalin (NGAL), kidney injury molecule 1 (KIM-1), interleukin 18 (lL-18), liver-type fatty acid-binding protein (L-FABP), tissue inhibitor of metalloproteinase 2 (TlMP-2), insulin-like growth factor binding protein 7 (IGFBP7), calprotectin, urine angiotensinogen (AGT), and urine microRNAs . These biomarkers can be classified into functional, damage and pre-injury phase biomarkers. Current evidence from clinical studies supports the use of new biomarkers in prevention and management of AKI. However, there is a caveat: these biomarkers are imperfect, just like serum creatinine. Both are an “aid to” rather than a substitute for clinical judgement. Through hands-on clinical experience in realistic clinical settings, these biomarkers will begin to enhance clinical practice in the same way that the evolution of cardiac injury biomarkers has led to earlier diagnosis of myocardial infarction, early and successful intervention and, through greater awareness of need, to even better biomarkers.