Objective        To design 3 different oral hydration therapies for out-patients with high risk for contrast-induced nephropathy (CIN) who undergoing contrast-enhanced CT scanning and determine their preventive effects on renal function so as to explore an effective and simple measure to prevent CIN.       Methods       A total of 74 consecutive out-patients (45 males and 29 females

mean age 63.79±8.81) with high risk for CIN undergoing enhanced spiral CT scanning in our hospital from January 2011 to September 2013 were enrolled in this study. They were randomly divided into 3 groups

conventional hydration group (n=27

taking 2 000 mL water on the day of scanning and then 1 500 mL on the second and third days after that)

intensive hydration group (n=22

taking 900 mL water in 1 h before scanning

500 mL once per hour for 3 consecutive hours after scanning and then 1 500 mL on the second and third days after that) and trial hydration group (n=25

taking 900 mL water in 1 h before scanning

500 mL within 0.5 h after scanning and then 1 500 mL on the second and third days). Indexes including serum creatinine (Scr) level

serum urea nitrogen level and serum Cys C level of 3 groups were measured before and in 24 and 72 h after the injection of contrast

and the results were analyzed by variance analysis.       Results       No CIN was observed in the 3 groups. There was no significant difference in Scr level

serum urea nitrogen level and serum Cys C level at the 3 time points among the 3 groups (P0.05). But the trial hydration program required shorter time and got better compliance in the patients.       Conclusion        In clinical practice

the trial hydration therapy effectively prevents the renal impairment induced by contrast for the out-patients with high risk of CIN. Our trial hydration program is easy to follow and suitable for outpatients.