Contrast-induced nephropathy fears ease

Ten years of clinical data from more than 30,000 patients suggest the estimated risk of sustaining renal damage from iodinated contrast media may have been blown out of proportion, according to Columbia University researchers. With proper scientific validation, contrast may be used even in patients with renal failure.

Iodinated contrast agents used on CT exams have been blamed for kidney dysfunction for decades, as the clinical literature propagated the concept of contrast-induced nephropathy. Most studies on the subject, however, lacked the means to distinguish contrast-induced nephropathy from other causes of the condition, said principal investigator Dr. Jeffrey Newhouse, director of the division of abdominal imaging at Columbia-Presbyterian Medical Center in New York City.

Newhouse and colleagues retrospectively reviewed electronic records for radiology, cardiology, and laboratory results stored in their clinical data warehouse from January 1995 through December 2004. The investigators identified a total of 32,161 patients who underwent imaging without iodinated contrast material. They compared the frequency and magnitude of serum creatinine changes in these patients with those reported in previously published articles that had correlated contrast media, serum creatinine levels, and nephropathy.

The researchers found that creatinine levels rose just as often in patients who did not receive contrast material as in those who did. Their findings will appear in the August issue of the American Journal of Roentgenology (2008;191:376-382).

More than half of the 32,161 patients who did not get contrast material showed a change of at least 25% in creatinine levels. About two in five showed changes of at least 0.4 mg/dL. These changes occurred in patients with both normal and abnormal initial creatinine values and were caused by a wide range of conditions, treatments, and laboratory variations that may alter creatinine levels, according to Newhouse.

These changes were not different from those published by the clinical literature on patients who underwent contrast-enhanced exams, he said.

Prior studies of the relationship between iodinated contrast material and renal function must be interpreted with caution because serum creatinine levels change frequently in the absence of iodinated contrast media material, Newhouse said. Future studies should include appropriate controls.

"We don't claim that IV contrast material never induces nephropathy, but it may do so less frequently and severely than previously thought," Newhouse said. "If subsequent experimentation proves its safety, it could be used more frequently in patients with renal failure."

For more information from the Diagnostic Imaging archives:

Milk may outperform barium as GI contrast medium

Oral fluids may dilute contrast reaction risk in patients with kidney disorders

Cheap drug protects against CT contrast-induced nephropathy

Nonionic contrast media prove safe in pediatric patients