Potential participants were identified by staff intensivists or resident physicians following admission to participating ICUs. We included critically ill adult patients at least 18 years of age who consented to participate in the trial, had central venous access and a foley catheter, required a contrast-enhanced CT of any organ system(s), and were considered 'at risk' for the development of CIN. We defined 'at risk' to include patients with at least one of the following at the time of randomization (i) a serum creatinine of > 106 µmol/L and or urea > 6 mmol/L, (ii) urine output of < 0.5 cc/kg over > 4 hrs or (iii) an increase in serum creatinine of > 50 µmol/L in < 24 hours. We stratified based on the presence or absence of diabetes defined as a history of treatment with oral hypoglycemics or insulin.