CT Scan Contrast Dye Harmless to Kidneys, Studies Show

The National Kidney Foundation warns that, in rare cases, CT scan contrast dye can cause a dangerous condition called contrast-induced nephropathy, or CIN. This marked decline in kidney function occurs in about 2 percent of the people who receive contrast agents for CT scans and certain other types of diagnostic imaging. It works fast, often in just two or three days.

But is contrast dye really to blame for these liver problems? A new meta-analysis published in the journal Annals of Emergency Medicine suggests that we’ve got CIN all wrong. The development of a kidney disorder in people who receive CT scan contrast is all just a misleading coincidence, the study seems to suggest.

Dr. Ryan Aycock and five colleagues dug through the literature to see how many instances of kidney damage they could attribute to contrast dye. They searched all the major medical databases, include Medline, CINAHL, and the Cochrane Library.

Out of a field of more than 14,000 articles, the team winnowed down their findings to just 28 studies that very specifically dealt with CT scans and three conditions: kidney injury, post-scan dialysis (or “renal replacement therapy”), and a factor called all-cause mortality, which describes all the deaths within a given population without filtering them by cause.

Their findings might make CIN a thing of the past.

Tracking CT Scan Contrast and Its Effect on the Kidneys

This research covered a very large sample size.

The 28 studies that Aycock and his team looked at involved more than 107,000 participants, all of whom experienced diagnostic imaging via CT scan. Some of them were given contrast dye, while others weren’t. Some in each group developed kidney problems. These were the numbers the researchers were looking for. In the end, the results spoke for themselves.

“We found no significant differences in our principal study outcomes between patients receiving contrast-enhanced CT versus those receiving noncontrast CT,” the paper’s authors wrote. “Given similar frequencies of acute kidney injury in patients receiving noncontrast CT, other patient- and illness-level factors, rather than the use of contrast material, likely contribute to the development of acute kidney injury.”

Previous Study Shows Similar Results

Aycock’s meta-analysis comes quick on the heels of similar findings presented in another recent paper published in the Annals of Emergency Medicine. Jeremiah Hinson and colleagues embarked on the largest controlled study of kidney injury following CT scans in an emergency room. In the end, they did not find a correlation between CT scan contrast dye and an increased risk of kidney problems.

“Intravenous contrast was not associated with an increased frequency of acute kidney injury,” the authors wrote.

Science is moving forward on CIN, and it has some good news: CT scan contrast agents don’t appear to be the risk to kidney health that we once feared.