A single-center, prospective, open-label, non-inferiority randomized controlled clinical trial was conducted at the ED of a tertiary hospital. The ED staff consisted of a mix of emergency medicine specialists, emergency medicine residents, and general practitioners.

Between August 10, 2024, and March 26, 2025, patients aged 18 and over who presented to the ED with creatinine levels above the reference range (1.2 mg/dl in men and 1.1 mg/dl in women) and underwent contrast-enhanced tomography were deemed eligible for inclusion in the study.

Eligible patients were randomly allocated in a 1:1 ratio to receive either bolus hydration or continuous hydration therapy. Permuted block randomization was employed at each participating site to distribute patients, stratified by age groups (18-44, 45-59, 60-74, and 75 years and older) and gender. This study did not use blinding. Both the implementers of the intervention and the researchers evaluating the outcome measures are aware of the intervention groups.

After the patients were divided into two groups, one group received bolus hydration therapy while the other group received continuous hydration therapy.

According to the literature, individuals with an ejection fraction of less than 40% got a half-dose hydration protocol.

The IV contrast agent used in the study was iohexol, which belongs to the non-ionic low osmolar contrast agent group. 300 mgI/ml 100 ml solutions were used, and the dose was adjusted between 80 and 100 ml depending on the imaging and the patient. In the majority of patients, 100 ml of contrast was administered, with an average of 98 ml of solution given in the bolus hydration group and an average of 96 ml of solution given in the continuous hydration group.

Patients were given control forms to provide follow-up blood samples 48-72 hours later and were asked to present to the ED with the form on the specified date. To inquire about the development of dialysis needs and mortality status, patients were contacted 30 days later to gather information.

Inclusion Criteria:

• Presented to the Emergency Department creatinine levels above the reference range (1.2 mg/dl in men and 1.1 mg/dl in women)
• Underwent contrast-enhanced tomography

Exclusion Criteria:

• Pregnancy
• Known allergy history to contrast agents
• Exposure to contrast agents within the last 72 hours
• Being on dialysis due to end-stage kidney disease
• Presenting with decompensated heart failure
• Patients who were unable to provide informed consent

Individual participant data will not be shared because the study involves single-center clinical data without a dedicated data-sharing infrastructure, and sharing these data may pose risks to participant privacy despite de-identification efforts.