CST3 and acute kidney injury: In patients classified using urine output only with disregard of P‐Creatinine, stage 2 AKI was associated with lower levels of corrected U‐Cystatin C levels (0.1 ± 0.1 mg/mmol) compared to stage 1 (0.3 ± 0.2 mg/mmol) and no oliguria (0.3 ± 0.3 mg/mmol) (P = .01 and 0.01, respectively).