Injected Substance Used With CT Scans Seems Safe for Kidneys: Study

An injected iodine-based substance often used to enhance the images produced by CT scans is safe for most patients, a new study reveals.

The so-called contrast material is used in at least half of the 80 million or more CT scans performed in the United States each year, according to study author Dr. Robert McDonald, a radiology resident at the Mayo Clinic in Rochester, Minn.

Some studies have linked iodine-based contrast CTs to kidney damage, a condition known as contrast-induced nephropathy. However, some of that research dates back to the 1950s, according to the new study.

To get a better idea of what the current risk might be, McDonald and colleagues analyzed data on almost 11,000 patients who underwent contrast-enhanced CT exams, comparing them to about the same number of patients who underwent non-contrast CT exams.

The investigators found no significant difference between the two groups' rates of acute kidney injury -- about 5 percent in each group -- or in their rates of emergency kidney dialysis in patients, or death within 30 days after their procedures.

The study groups included people with reduced kidney function and high-risk conditions -- such as heart failure and diabetes -- that are believed to predispose patients to kidney injury, according to the study published online Sept. 9 in the journal Radiology.

"These results challenge long-held assumptions regarding the presumed [kidney-toxic] risk of intravenous contrast material," McDonald said in a journal news release. "We hope that our findings will help refine the safety profile of these contrast agents."

More information

The U.S. National Library of Medicine has more about CT scans.