Sample Size Since there is no similar study in the literature and considering a previous work of our team, in which we measured the urinary levels of HSP72 as a biomarker just at the time of diagnosis of AKI, of the 56 patients included, only 17 (30.4%) developed AKI. The mean urinary levels of HSP72 in patients who did not develop AKI were 0.27±0.16 ng/ml, whereas in those diagnosed with AKI, the mean value was 4.78±1.92 ng/ml. Considering urinary levels of HSP72 in 56 patients, the mean was 1.64 ± 2.34 ng/ml. Making a theoretical model where we consider a possible reduction of 50% of the levels of the biomarker gives us a value of 0.82 ng/ml and using the formula of sample size for independent means with the difference of means of 0.82 and equal variances with a confidence level of 95% and a power of 80%, gives us n of 45 subjects per group. Therefore, we will recruit 90 patients for this study. When 20 patients have been recruited in the study per group, an interim analysis will be performed to decide on the basis of the results if the study is continued or permanently discontinued.