Available markers of acute kidney injury (AKI) lack sensitivity and specificity; consequently, diagnosis of AKI is delayed and Grade-I AKI is commonly unrecognized. We hypothesized that urinary interleukin (IL) 6 (IL-6) and 18 (IL-18) are sensitive and specific markers of AKI. Urine samples from healthy dogs, dogs with lower urinary tract disease (LUTD), chronic kidney disease (CKD), acute kidney injury (AKI) and at risk for AKI, were collected. Urine concentrations of IL-6 and 18 were measured using ELISA and corrected to urinary creatinine (uIL-6,18/uCr). Sixty-six dogs were included. There was a positive correlation between IL-6 and IL-18 (p<0.001, r-0.65). Median uIL-6/uCr of healthy, LUTD, CKD, AKI and dogs at risk were 0.026 pg/mg (range: 0.01–2.28), 0.04 pg/mg (range: 0.02–2.93), 0.08 pg/mg (range: 0.04–8.28), 0.46 pg/mg (range: 0.06–58.05) and 6.5 pg/mg (range: 0.04–19.74), respectively. Median uIL-18/uCr was 0.025 pg/mg (range: 0.01–0.14), 0.03 pg/mg (range: 0.02–0.26), 0.08 pg/mg (range:0.03–4.29), 0.32 pg/mg (range:0.01–5.38) and 0.12 pg/mg (range: 0.03–0.95), respectively. There was a significant difference in uIL-6/uCr and uIL-18/uCr among the study groups, with both higher in the AKI group compared with other groups, except uIL-18/uCr, which was not different between the AKI and CKD groups. Median uIL-6/uCr and uIL-18/uCr of dogs at risk for AKI, were higher compared with healthy dogs (p=0.034, p=0.045, respectively). ROC analysis of uIL-6/uCr and uIL-18/uCr as AKI predictors had an area under the curve of 0.85 and 0.78, respectively. uIL-6/uCr and uIL-18/uCr cut-off points of 0.11 and 0.13 were associated with sensitivity and specificity of 96% and 70%, respectively, and 83% and 70%, respectively. In conclusion, IL-6 and IL-18 are sensitive and specific markers of AKI.

Disclosures

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