The urinary levels of prostanoid metabolites predict acute kidney injury in heterogeneous adult Japanese ICU patients: a prospective observational study

Background: Acute kidney injury (AKI) is frequently observed in critically ill patients in the intensive care unit (ICU) and is associated with increased mortality. Prostanoids regulate numerous biological functions, including hemodynamics and renal tubular transport. We herein investigated the ability of urinary prostanoid metabolites to predict the onset of AKI in critically ill adult patients. Methods: The current study was conducted as a prospective observational study. Urine of patients admitted to the ICU at Okayama University Hospital was collected and the urinary levels of prostaglandin E₂ (PGE₂), PGI₂ metabolite (2,3-dinor-6-OXO-PGF_1α), thromboxane A₂ (TXA₂) metabolite (11-dehydro-TXB₂) were determined. Results: Of the 93 patients, 24 developed AKI (AKIN criteria). Surgical intervention (93, 75 %) was the leading cause of ICU admission. Overall, the ratio of the level of serum Cr on Day 1 after ICU admission to that observed at baseline positively correlated with the urinary 2,3-dinor-6-OXO-PGF_1α/Cr (r = 0.57, p < 0.0001) and 11-dehydro-TXB₂/Cr (r = 0.47, p < 0.0001) ratios. In 16 cases of de novo AKI, the urinary 2,3-dinor-6-OXO-PGF_1α/Cr and 11-dehydro-TXB₂/Cr values were significantly elevated compared with that observed in the non-AKI group, whereas the urinary PGE₂/Cr values were not. The urinary 2,3-dinor-6-OXO-PGF_1α/Cr ratio exhibited the best diagnostic and predictive performance among the prostanoid metabolites according to the receiver operating characteristic (ROC) analysis [ROC–area under the curve (AUC): 0.75]. Conclusions: Taken together, these results demonstrate that the urinary 2,3-dinor-6-OXO-PGF_1α/Cr and 11-dehydro-TXB₂/Cr ratios are associated with the subsequent onset of AKI and poor outcomes in adult heterogeneous ICU patients.