The Association of Preoperative Biomarker Levels in Adult Patients with Congenital Heart Disease and Postoperative Acute Kidney Injury

BACKGROUND Although acute kidney injury (AKI) is a frequent complication in adults with congenital heart disease undergoing cardiac surgery, tools for preoperative risk stratification are limited. Urinary biomarkers may reflect underlying tubular reserve or stress, revealing susceptibility to AKI that is not detected by serum creatinine alone. METHODS We conducted a prospective cohort study of adults aged 18-40 years with congenital heart disease, baseline estimated glomerular filtration rate ≥60 mL/min/1.73 m 2 , undergoing cardiac surgery requiring cardiopulmonary bypass. Preoperative urine samples were collected within 4 weeks before surgery. The primary outcome was postoperative AKI, defined by Kidney Disease: Improving Global Outcomes criteria. Associations between preoperative urinary biomarkers and AKI were evaluated using logistic regression. Discrimination was assessed using the area under the receiver operating characteristic curves (AUC). RESULTS Fifty participants were included; 16 (32%) developed postoperative AKI. Baseline demographics and operative characteristics were similar between groups. Patients who developed AKI had lower preoperative urinary uromodulin and higher urinary Dickkopf-related protein 3 and kidney injury molecule-1 compared with those without AKI, while neutrophil gelatinase–associated lipocalin did not differ. Lower uromodulin, higher Dickkopf-related protein 3, and kidney injury molecule-1 were independently associated with increased odds of AKI. Uromodulin and Dickkopf-related protein 3 demonstrated excellent discrimination for AKI (AUC 0.94 and 0.95, respectively), while kidney injury molecule-1 showed fair discrimination (AUC 0.76). CONCLUSIONS In adults with congenital heart disease undergoing cardiac surgery , preoperative urinary uromodulin and DKK3 strongly predict postoperative AKI. These biomarkers may improve individualized risk assessment and perioperative management strategies.