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.

Inclusion Criteria:

• Patients aged 18 years and older.
• Patients with an estimated Glomerular Filtration Rate (eGFR) between 15-59 mL/min/1.73 m².
• Patients undergoing contrast-enhanced computed tomography (CT) in the emergency department.
• Patients who have provided written informed consent.

Exclusion Criteria:

• Pregnant women.
• Patients with end-stage renal disease (ESRD) receiving dialysis or those with an eGFR <15 mL/min/1.73 m².
• Patients presenting with decompensated heart failure.
• Patients with a known allergy to iodinated contrast media.
• Patients with contrast media exposure within the last 72 hours.
• Patients for whom oral intake is contraindicated or who cannot tolerate oral intake