In Emergency Situations, Should Serum Creatinine Be Checked in All Patients Before Performing Second Contrast CT Examinations Within 24 Hours?

Objective

The aim of this study was to determine the frequency of contrast-induced nephropathy (CIN) in patients undergoing repeat contrast-enhanced computed tomographic (CT) examinations within 24 hours, as well as associated risk factors.

Materials and Methods

Through a search of medical and radiologic records, patients who underwent 2 contrast-enhanced CT examinations within 24 hours during a 4-year period (2003-2006), with available serum creatinine measurements before and after CT imaging were included. Medical records were reviewed for demographic data, risk factors, renal status, and CT contrast volume. The frequency of CIN was calculated, and odds ratios of risk factors were determined.

Results

There were 164 patients (90 men, 74 women; mean age, 56.3 years), with an average baseline serum creatinine level of 1.02 ± 0.73 mg/dL (range, 0.3-6.6 mg/dL). Three hundred twenty-eight CT examinations were performed: 2 in each patient, at an average interval of 11.4 hours. The mean doses of contrast medium used for the first and second CT examinations were 126.2 and 123.4 mL, respectively. Twenty-one patients (12.8%) developed CIN. Comparing patients with and without CIN, the only statistically significant risk factor for CIN was an increase in serum creatinine between the first and second CT examinations, with an odds ratio of 18 (P < .005).

Conclusion

The incidence of CIN in patients who underwent repeat contrast-enhanced CT examinations was 12.8%. An increase in serum creatinine between the first and second CT examinations was highly associated with CIN and may serve as a risk factor for developing CIN.

Key Words: Contrast-induced nephropathy, computed tomography, serum creatinine