Evaluation of serum and urine neutrophil gelatinase-associated lipocalin and cystatin C as biomarkers of acute kidney injury in horses

Abstract

Introduction Diagnosis of acute kidney injury (AKI) in horses is difficult at the subclinical stage, due to nonspecific clinical signs. The aim of this study was to evaluate the concentrations of selected serum and urinary biomarkers in healthy horses, horses at risk of AKI, and those with clinical AKI. Material and Methods Thirty healthy horses, 30 horses at risk of AKI and 11 horses with clinical AKI and azotaemia were included in the study. Serum and urinary neutrophil gelatinase-associated lipocalin (NGAL) and cystatin C were measured using commercially available enzyme immunoassay tests. Results The median and (in parentheses) first and third quartile concentrations of selected biomarkers in healthy horses, horses at risk of AKI and horses with AKI were respectively as follows: serum cystatin C – 0.25 (0.19–0.37), 0.23 (0.15–0.37) and 0.61 (0.37–1.13) mg/L; serum NGAL – 50.5 (38.8–58.8), 51.1 (40.4–66.9) and 98.1 (59.4–128.2) ng/mL; urinary NGAL – 20.7 (17.9–24.5), 32.3 (32.7–55.8) and 36.6 (26.8–89.9) ng/mL; and urinary cystatin C – 0.1 (0.07–0.13), 0.13 (0.1–0.2) and 0.34 (0.22–0.37) mg/L. There were significant differences in the concentration of all biomarkers between the healthy and AKI-affected horses. Conclusion Horses with AKI all had biomarker concentrations higher than the healthy horses. None of the biomarkers made azotaemia recognisable in all affected horses. The obtained results indicate the need to create a serum and urinary biomarker panel to detect AKI.

Biomarkers of Kidney Disease in Horses: A Review of the Current Literature

“…Regarding the assay validation (phase I), one publication uses a human latex immunoassay, but has to conclude that the test does not work for equine samples [ 24 ]. The remaining two publications, both use a commercially available ELISA kit (MyBioSource, San Diego, CA, USA, catalogue number MBS022947) [ 25 , 26 ]. This kit is validated by the manufacturer for use with serum and urine samples of equine origin, but no data on this validation are available in the literature.…”

“…Urine and serum cystatin C concentrations were reported to be higher in horses with AKI versus healthy horses without AKI [ 25 ]. Horses that were determined to be at risk for AKI (with colic but without endotoxemia, sepsis or systemic inflammatory response syndrome, and with absence of azotemia) were shown to have elevated serum and urine cystatin C concentrations [ 25 ]. This suggests that cystatin C has potential to detect early AKI before serum creatinine concentrations increase.…”

“…Siwinska et al reported on clinical performance of cystatin C with the determination of optimal cut off values and their sensitivity and specificity to diagnose AKI (Phase III) [ 25 ]. The optimal cut off value for serum cystatin C was 0.53 mg/L with a sensitivity and specificity of 0.64 and 0.85; for urinary cystatin C this was at 0.20 mg/L with a sensitivity and specificity of 0.82 and 0.85 [ 25 ].…”

“…Siwinska et al reported on clinical performance of cystatin C with the determination of optimal cut off values and their sensitivity and specificity to diagnose AKI (Phase III) [ 25 ]. The optimal cut off value for serum cystatin C was 0.53 mg/L with a sensitivity and specificity of 0.64 and 0.85; for urinary cystatin C this was at 0.20 mg/L with a sensitivity and specificity of 0.82 and 0.85 [ 25 ]. The serum cystatin C concentrations in the above mentioned Theileria equi infected horses reported by Ahmadpour et al [ 26 ] were clearly higher than this identified optimal cut of value to identify AKI set by Siwinska et al [ 25 ].…”

Neutrophil gelatinase-associated lipocalin in dehydrated horses: A prospective case-control study

“…researched. Nevertheless, signi cant differences in the concentration of NGAL in serum and urine were already found between healthy and AKI-affected horses [23].…”