Increased Retinol Levels in Patients with Cardiac Surgery-Associated Acute Kidney Injury-A Prospective Single-Center...

Acute kidney injury (AKI) is a frequent and prognostically important complication of cardiac surgery, yet early risk stratification remains challenging. The purpose of this prospective exploratory study was to determine whether preoperative vitamin levels differ in patients who develop cardiac surgery-associated AKI.

Consecutive patients scheduled for cardiac surgery due to coronary artery disease and/or severe aortic stenosis between October 2024 and July 2025 were included. Fourteen patients (16.1%) had preoperative eGFR below 60 mL/min. Preoperative serum levels of vitamin A (retinol), vitamin E (α-tocopherol), and vitamin D (25-hydroxyvitamin D3) were measured.

A total of 87 patients (72 males (82.8%) with a median (Q1-Q3) age of 66 (61.5-71) years) were included in the study. Cardiac surgery-associated AKI occurred in 36 (41.4%), as a mild and transient impairment, with only two patients with a more severe stage requiring temporary renal replacement therapy. Patients who developed AKI had significantly higher preoperative retinol levels (p = 0.046). Retinol concentrations correlated positively with preoperative creatinine (Spearman's rho 0.321, p = 0.002), postoperative day 0 creatinine (Spearman's rho 0.333, p = 0.002), and postoperative day 1 creatinine (Spearman's rho 0.268, p = 0.012), and negatively with preoperative eGFR (Spearman's rho -0.288, p = 0.007). Tocopherol and 25(OH)D3 did not differ significantly between subgroups. No difference in vitamin levels was observed between patients with and without diabetes.

Increased preoperative retinol levels were associated with cardiac surgery-associated AKI and correlated with perioperative renal dysfunction. Retinol may reflect impaired kidney handling of retinol and identify increased renal vulnerability in cardiac surgery patients. Retinol may represent a hypothesis-generating biomarker of cardiac surgery-associated AKI risk that warrants confirmation in larger cohorts.