On the day of AKI diagnosis, patients with late AKI had a higher illness severity, APACHEII score, SOFA score, bicarbonate radical, serum creatinine, BUN and cystatin C levels, than those with early AKI (21.0 vs. 15.0, 8.0 vs. 3.0, 21.4 vs. 17.7, 156.0 vs. 125.0, 15.3 vs. 8.5, and 1.7 vs. 0.8, respectively, all p values <0.05). Here, CST3 is linked to acute kidney injury.