Are screening serum creatinine levels necessary prior to outpatient CT examinations?

To determine the percentage of outpatients with elevated serum creatinine levels (>/=2.0 mg/dL [177 micromol/L]) and associated reported risk factors for contrast material-induced nephrotoxic reactions (eg, diabetes, renal disease, male, age >/= 60 years, chemotherapy) who undergo computed tomography (CT) and to define a true high-risk population.

The serum creatinine levels were obtained in a total of 2,034 consecutive outpatients (969 male, 1,065 female) who underwent contrast material-enhanced CT. In addition, selected patient charts were reviewed to determine the presence of risk factors for contrast material-induced nephrotoxic reactions.

Only 66 (3.2%) had an elevated serum creatinine level. Risk factors were identified in 64 of the 66 (97%) patients with an elevated serum creatinine level. Renal disease was present in 62 of the 66 (94%) patients. Two of the 66 patients with an elevated creatinine level had no identifiable risk factors, representing 0.1% of the total number of patients.

The data suggest that the majority of patients with a serum creatinine level of at least 2.0 mg/dL (177 micromol/L) will be identified by screening for risk factors. Careful patient screening, especially for renal disease, at the time of scheduling could result in considerable savings in terms of radiology man-hours expended and laboratory costs.