Contrast-Associated Acute Kidney Injury

This is a single-center, prospective observational study. We aim to evaluate the performance of transdermal glomerular filtration rate (TGFR) compared with baseline estimated glomerular filtration rate (eGFR) for early prediction of contrast-associated acute kidney injury (CA-AKI) in emergency patients scheduled for contrast-enhanced CT. Eligible participants are adult emergency patients with baseline eGFR between 15 and 120 mL/min/1.73m². TGFR monitoring will be performed during the peri-contrast CT period. We will collect clinical and laboratory data and follow up renal function after contrast exposure to analyze the predictive value of TGFR for CA-AKI. No extra therapeutic interventions will be applied in this study.

Iodinated contrast dye used during computed tomography (CT) scans can sometimes cause kidney stress or damage, known as contrast-associated acute kidney injury (CA-AKI). Currently, doctors evaluate a patient's kidney safety using standard estimated glomerular filtration rate (eGFR). However, standard eGFR is calculated for an average body size rather than an individual's actual body size, which can misrepresent a person's true kidney excretion capacity. This study aims to evaluate whether comparing the volume of contrast dye directly to a patient's true, individualized kidney function (the contrast volume-to-absolute GFR ratio) can accurately predict the risk of developing kidney injury after an intravenous contrast-enhanced CT scan. This is a prospective, observational study involving adult outpatients who are already scheduled for a clinically necessary contrast-enhanced CT scan. Participation is observational and does not alter the patient's planned scan, medical treatment, or the amount of contrast dye administered by their healthcare team. Participants will: * Have their baseline kidney function assessed through a routine blood test (serum creatinine) within 48 hours prior to their CT scan. * Have their height and weight recorded to calculate their individualized, absolute kidney function. * Complete a follow-up blood test (serum creatinine) 48 to 72 hours after the CT scan to evaluate any changes in kidney function. Researchers will analyze whether the ratio of contrast volume to absolute kidney function reliably identifies patients at higher risk of contrast-associated kidney complications, helping to establish safer, personalized contrast dosing strategies in the future.

This study is planned to be conducted by emergency physicians between November 7, 2025, and December 7, 2026. Inclusion and Exclusion Criteria The study will include adult patients aged 18 years and older who are considered at risk for Contrast-Associated Acute Kidney Injury (CA-AKI), with an estimated Glomerular Filtration Rate (eGFR) between 15-59 ml/min/1.73 m², a clinical indication for contrast-enhanced CT, and who have provided signed informed consent. Exclusion criteria are as follows: Pregnant women. Patients with a known contrast media allergy. Contrast media exposure within the last 72 hours. End-stage renal disease (ESRD) with eGFR \<15 ml/min/1.73 m² or those receiving dialysis. Patients with clinical decompensated heart failure. Patients for whom oral intake is contraindicated or not tolerated. Randomization and Interventions Prior to randomization, the oral intake capacity of eligible patients will be verified. Participants will be randomized into two groups-IV hydration and oral hydration-at a 1:1 ratio using stratified block randomization based on age and gender. IV Hydration Group: Isotonic 0.9% NaCl solution will be administered. The regimen consists of 3 ml/kg for 1 hour pre-procedure, followed by 2 ml/kg/hour for 4 hours post-procedure. Patients with an ejection fraction (EF) \<40% will receive half-doses (1.5 ml/kg pre-procedure; 1 ml/kg/hour for 4 hours post-procedure). Oral Hydration Group: Drinking water will be administered under nursing supervision. The regimen consists of 500 ml 1 hour pre-procedure and 125 ml/hour for 4 hours post-procedure. Patients with an EF \<40% will receive half-doses (250 ml pre-procedure; 62.5 ml/hour post-procedure). Follow-up and Outcome Measures Baseline renal function tests will be obtained from all patients prior to the protocol. Patients will be re-evaluated for CA-AKI via blood samples taken 48-72 hours after contrast administration. Furthermore, eGFR changes will be calculated using the Modification of Diet in Renal Disease (MDRD) formula. Mehran Risk Scores will also be determined for each patient. Long-term outcomes, including progression to ESRD (requirement for dialysis) and mortality within 1 month, as well as creatinine levels between days 30-45, will be assessed.