Perioperative dynamics of selenoproteins and risk of cardiac surgery–associated acute kidney injury

Cardiac surgery-associated acute kidney injury (CSA-AKI) affects over 20% of patients and is associated with perioperative mortality and long-term renal impairment. Reliable early biomarkers remain limited. Selenoproteins, including glutathione peroxidases (GPX1, GPX3) and selenoprotein P (SEPP1), are critical for redox homeostasis, but their perioperative changes in CSA-AKI remain unclear. This study aimed to characterize selenoprotein dynamics and explore their association with renal function and CSA-AKI. In this prospective observational cohort study, 99 adult patients undergoing cardiac surgery were enrolled, serum and urine samples were collected preoperatively and at 24/48 h postoperatively. SEPP1, GPX1, GPX3, and KIM-1 were measured. Mixed-effects, correlation, and logistic regression assessed selenoprotein dynamics and associations with CSA-AKI, with an exploratory model including age and preoperative SEPP1. Among 89 analyzed patients, 22 (24.7%) developed AKI. Univariable analyses showed that lower perioperative SEPP1 levels, attenuated urinary SEPP1 increases, and greater serum GPX1 decreases were associated with higher odds of CSA-AKI; older age, hypertension, and longer operation time were also associated with CSA-AKI. Postoperatively, serum SEPP1 declined markedly, remaining lower in AKI patients. Urinary SEPP1 increased significantly in non-AKI patients. Changes in GPX1 and GPX3 differed between AKI and non-AKI groups. Serum SEPP1 correlated positively with eGFR and inversely with creatinine and cystatin C. An exploratory model incorporating age and preoperative serum SEPP1 yielded an apparent AUC of 0.818. In summary, perioperative alterations in selenoproteins (GPX1, GPX3, SEPP1) are closely linked to CSA-AKI. Preoperative SEPP1 combined with clinical variables may enable early risk prediction and support timely intervention.