Biomarkers of Acute Kidney Injury after Cardiac Surgery: A Narrative Review

Abstract

Cardiac surgery-associated acute kidney injury (CSA-AKI) is a major and serious complication in patients undergoing cardiac surgery and is independently associated with perioperative mortality and mortality. Therapeutic intervention aiming at reversing kidney dysfunction seems disappointing across multiple settings. Consequently, attention has shifted from treatment to prevention and early detection. The Kidney Disease: Improving Global Outcomes (KDIGO) guidelines have unified diagnostic standards mainly based on the serum creatinine (Scr) level or urine output, but neither marker is kidney specific. Efforts have been made to identify novel biomarkers with high sensitivity and specificity. The diagnostic capabilities of neutrophil gelatinase-associated lipocalin (NGAL) and G1 cell cycle arrest biomarker as biomarkers have been confirmed in a large number of clinical trials. The utility of biomarkers of cardiac function and inflammation has been validated in clinical studies. Aiming to offer valuable information for further research, we summarize the progress in defining current markers relevant to CSA-AKI in the last three years.

Figure 1

Biomarkers of cardiac surgery-associated acute kidney injury (CSA-AKI). Biomarkers of CSA-AKI are divided into four categories including renal tubule-associated biomarkers, nonrenal tubule-associated biomarkers, biomarkers of cardiac function, and biomarkers of inflammation. Other biomarkers that cannot be classified into the above types are listed as one category at the top left. CK-MB: creatine kinase-MB, H-FABP: heart fatty acid binding protein, NT-proBNP: N-tnd persistederminal prohormone of brain natriuretic, AngII: angiotensin II, NGAL: neutrophil gelatinase-associated lipocalin, TIMP-2: tissue inhibitor of metalloproteinases 2, IGFBP-7: insulin-like growth factor-binding protein 7, ApoM: apolipoprotein M, UMOD: urinary uromodulin, MMP-7: matrix metalloproteinase-7, IL: interleukin, TNF-α: tumor necrosis factor alpha, MCP-1: monocyte chemotactic protein-1, Gal-3: galectin-3, GSN: gelsolin, CYR61: cysteine-rich protein 61, GDF-15: growth differentiation factor 15, RFR: renal functional reserve, Alb: albumin, UA: uric acid, Hp2-2: 2-2 phenotype of haptoglobin, Hb: hemoglobin, PO₂: oxygen tension, MiR-21: microRNA-21, UmtDNA: urinary mitochondrial DNA, and FGF23: fibroblast growth factor 23.