Magyar A, et al. - Using data from a prospective cohort study of 150 adult cardiac surgical patients, researchers assessed heme oxygenase-1 (HO-1) induction after cardiac surgery involving cardiopulmonary bypass (CPB) and for its association with acute kidney injury (AKI). Before, immediately after and 24 hours post-CPB, HO-1 measurements were performed. AKI was seen in 23.3% of patients and was not correlated with an early elevation of HO-1 following CPB in all patients, while those suffering from AKI developed a second burst of HO-1 24 hours following CBP. The HO-1 concentrations dropped to baseline values in patients without AKI, and early HO-1 induction was correlated with CPB time; the ones 24 hours later lost this association. The association of the second HO-1 burst 24 hours after CPB could help to differentiate the causality of AKI in patients undergoing CBP, and help adapt stratification and management of patients.