Purpose: In critically ill patients, acute kidney injury (AKI) is a devastating problem often associated with adverse outcomes. Depending on the conventional markers for diagnosis of AKI, an undesirable delay in the diagnosis and initiation of treatment has occurred. Thus, it is challenging to find a biomarker for early diagnosis of AKI. We sought to evaluate urinary YKL-40 as a biomarker for early diagnosis of AKI among critically ill patients compared with conventional markers and to assess its relation to the severity of AKI.
Methods: Thirty-six patients without AKI at the time of ICU admission who enrolled in this prospective cohort study had the following measured: serum creatinine as well as urine YKL-40 at admission and thereafter at 4 time intervals (0, 12, and 24 ± 48 h) (therefore, we studied 94 urine samples in 36 patients). Urine YKL-40 was quantified by enzyme-linked immunosorbent assay (ELISA). AKI was defined using the Kidney Disease Improving Global Outcomes (KDIGO) criteria, which include three stages (1, 2, and 3) of progressive renal dysfunction.
Results: In this study, 18 (50%) patients developed AKI within 48-72 h. Moreover, urine YKL-40 increased significantly within 12 h in patients who developed AKI (n = 18, 11.75 ± 1.94), but not in non-AKI patients (n = 18, 5.66 ± 3.42) ng/ml (P < 0.001) and, at the same time, we did not find any significant difference in the serum creatinine levels between the two groups. In addition, AKI group showed rising levels with KIDGO classes.
Conclusion: In this pilot study we found that urinary YKL-40 can be used as a valuable and noninvasive marker for early diagnosis of AKI among critically ill patients in ICU as compared to conventional markers and its level is increasing with the severity of AKI classes. However, the small sample size is important limitation. Therefore, large multicenter studies may be needed to confirm it.
Keywords: Acute kidney injury; Critical ill patients; ICU; YKL-40.