Table 2.
Potential biomarkers of contrast-induced acute kidney injury
| Biomarker | Location in kidney | Method of detection |
|---|---|---|
| Cystatin C (Cys-C) | Produced by all nucleated cells, filtered by glomerulus, and reabsorbed by proximal tubule cells | Enzyme-linked immunosorbent assay (ELISA) and nephelometric and turbidometric assays |
| Neutrophil gelatinase-associated lipocalin (NGAL) | Expression upregulated in proximal tubule cells after renal injury | ELISA, immunoblotting, and turbidometric assay |
| N-Acetyl-β-glucosaminidase (NAG) | Proximal tubule lysosomal enzyme | ELISA and spectrophotometric assay |
| Kidney injury molecule-1 (KIM-1) | Upregulated in dedifferentiated proximal tubule cells | ELISA and immunoblotting |
| L-fatty acid binding protein (L-FABP) | Expressed in proximal tubule cells | ELISA |
| Interleukin-18 (IL-18) | Expressed in distal tubule cells; expression may be induced in proximal tubules | ELISA |
| Midkine (MK) | Expressed in proximal tubule cells | ELISA |
| Retinol-binding protein (RBP) | Filtered by the glomerulus and reabsorbed by the proximal tubule cells | ELISA and nephelometric assay |
| β2-Microglobulin (β2M) | Filtered by the glomerulus and reabsorbed by the proximal tubule cells | ELISA and nephelometric assay |
Notes: Particle-enhanced turbidometric and nephelometric immunoassays are relatively quick, avoiding the need for sample pretreatment and allowing use of less sample. Similarly, the development of bead-based multiplex immunoassays will allow the detection of several molecules at the same time compared with conventional ELISA.