Implementation of therapy for acute kidney injury (AKI) depends on successful prediction of individual patient prognosis. Clinical markers as serum creatinine (sCr) have limitations in sensitivity and early response. The aim of the study was to identify novel molecules in urine which show altered levels in response to AKI and investigate their value as predictors of recovery. Changes in the urinary proteome were here investigated in a cohort of 88 subjects (55 AKI patients and 33 healthy donors) grouped in discovery and validation independent cohorts. Patients’ urine was collected at three time points: within the first 48 h after diagnosis(T1), at 7 days of follow-up(T2) and at discharge of Nephrology(T3). Differential gel electrophoresis was performed and data were confirmed by Western blot (WB), liquid chromatography/mass spectrometry (LC-MS/MS) and enzyme-linked immunosorbent assay (ELISA). Retinol binding protein 4 (RBP4) and kininogen-1 (KNG1) were found significantly altered following AKI. RBP4 increased at T1, and progressively decreased towards normalization. Maintained decrease was observed for KNG1 from T1. Individual patient response along time revealed RBP4 responds to recovery earlier than sCr. In conclusion, KNG1 and RBP4 respond to AKI. By monitoring RBP4, patient’s recovery can be anticipated pointing to a role of RBP4 in prognosis evaluation.

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Background: Epidemiological studies of acute kidney injury (AKI) have focused on patients admitted to intensive care units (ICUs), and several have studied hospitalized non-ICU patients, but analysis of patients referred to Nephrology is sparse. We analyzed factors associated with short- and long-term morbimortality among hospitalized non-ICU patients with AKI who were referred to Nephrology. Methods: A retrospective study with data prospectively collected from 170 non-ICU patients, with referral to the Nephrology Unit, recruited over a 4-year period, was performed. AKI was classified according to the criteria based on risk, injury, failure, loss of kidney function and end-stage kidney disease (RIFLE). Risk factors that could influence prognosis of AKI and long-term mortality were analyzed at admission. Early on, 1- and 10-year mortalities were correlated with AKI RIFLE class, clinical and demographic characteristics. Results: Most patients were >65 years, with multiple comorbidities and frequent drug intake history. Median Charlson score was 6. Twenty-five percent of patients with previously unknown chronic kidney disease (CKD) were diagnosed with CKD during the study. Dialysis was required in 13.5% of patients. Hospital deaths were 22.4% and significantly associated with older age, RIFLE class L, higher peak serum creatinine, oliguria and decreased serum albumin levels. One-year (38.8%) and 10-year (68.8%) mortalities were significantly associated with age, prior cardiovascular disease, prior CKD and RIFLE class L. According to the Cox proportional hazard model, age, prior CKD and RIFLE class L were independent risk factors of death at 1 and 10 years. Conclusions: AKI in hospitalized non-ICU patients is associated with high early and late mortality. This study increases our understanding of AKI among this specific population and can improve their management.

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