Review Article

Role of New Biomarkers: Functional and Structural Damage

Table 3

Properties of renal biomarkers.

Biomarker
(sources)
Origin in AKI casesPhysiological functionSignificance of riseStudied clinical settings Assay platform

NGAL
(urine and circulating)
Urine: local synthesis in distal nephron in response to injury and secreted into urine
Circulating: synthesized systemically in response to renal injury, filtered by glomerulus, and uptaken by proximal tubular cells with a little amount secreted in the urine
Bacteriostatic action, antioxidant effect, and growth and differentiation factorTubular injury (ischemia and nephrotoxins)(i) Early detection of AKI after cardiac surgery in heterogeneous ICU population, in the emergency department, and after administration of nephrotoxins
(ii) Risk stratification
(iii) Prognostic marker after kidney transplantation
(iv) Monitoring interventional trials in AKI
(v) Prognosis of dialysis requirement in case of AKI establishment
(vi) Prognosis of mortality
WB-ELISA-PETIA-POCT-CMIA

Cystatin C
(urine and circulating)
Produced at a constant rate by nucleated cells, filtered by glomerulus, and almost completely reabsorbed in the proximal tubulesInhibitor of lysosomal proteases and extracellular inhibitor of cysteine proteasesChange in GFR (proximal tubule injury)(i) Early detection of AKI after cardiac surgery in heterogeneous ICU population and after administration of nephrotoxins
(ii) Prognosis of mortality
PENIA-PETIA-ELISA

KIM-1
(urine)
Type 1 transmembrane protein that is highly
expressed in dedifferentiated proximal tubule epithelial
cells after ischemic or toxic injury and is not detectable in
normal tissue
Regeneration process after epithelial injury, scavenger receptor for the removal of dead cells from tubular lumen through phagocytosisTubular injury (ischemia and nephrotoxins)(i) Early detection of AKI after cardiac surgery and after administration of nephrotoxins
(ii) Prognosis of dialysis requirement in case of AKI establishment
(iii) Prognosis of mortality
WB-ELISA

IL-18
(urine)
Proinflammatory cytokineoriginates from tubular epithelial cells Inflammation and immunomodulation mediatorTubular injury
(ischemia and nephrotoxins)
(i) Early detection of AKI after cardiac surgery in heterogeneous ICU population
(ii) Prognostic marker after kidney transplantation
(iii) Prognosis of mortality
ELISA

L-FABP
(urine and circulating)
Production in the liver determines blood levels. Renal L-FABP is found in cytoplasm of the proximal tubulesRenal L-FABP helps maintain low levels of free fat acids in the cytoplasmTubular injury (ischemia and nephrotoxins)(i) Early detection of AKI after cardiac surgery
(ii) Prognosis of mortality
ELISA

ELISA: enzyme-linked immunosorbent assay, PENIA: particle-enhanced nephelometric immunoassay, PETIA: particle-enhanced turbidimetric immunoassay, WB: western blot, POCT: point-of-care test (triage), CMIA: chemiluminescent microparticle immunoassay ARCHITECT automated platform).