Written by Nickolas Srica
Spoon Feed
IV contrast doses used for CT scans appear to fall below the toxic threshold for nephrotoxicity, with no convincing evidence they cause acute kidney injury (AKI) in most patients.
Kidneys live to dye another day…
This was a narrative review and toxicological perspective examining whether iodinated contrast used in CT imaging causes AKI. The authors argue that prior concern for contrast-associated AKI (CA-AKI) is largely based on older, confounded observational data, particularly from high-dose contrast exposure in percutaneous coronary intervention (PCI), which may not be generalizable to the much lower doses used in CT (typically 60–120 mL).
Using the concept of a toxicological threshold of concern (TTC; check out the image below!), the authors propose that toxicity only occurs above a certain dose, with no risk below a certain dose. Evidence from multiple large retrospective and meta-analytic studies reviewed (e.g., Hinson 2017, Aycock 2018, Ehmann 2023) consistently shows no association between IV contrast for CT and AKI, dialysis, or long-term renal outcomes.
In contrast (no pun intended), PCI involves substantially higher and variable contrast doses (200–900 mL), where a dose-dependent relationship with AKI has been demonstrated, supporting that toxicity may occur at these much higher doses. The authors conclude that CT contrast dosing likely falls below the TTC (~120 mL).
Limitations include reliance on retrospective data and the possibility of rare or high-risk subgroups (e.g., severe baseline CKD, repeated exposures) where risk may still exist. More prospective RCT data would allow for more definitive statements to be made here.
How does this change my practice?
This supports growing emergency medicine evidence that contrast-enhanced CT should not be routinely withheld or delayed due to fear of AKI, especially when clinically indicated. In my own practice, I will continue to prioritize diagnostic yield over the theoretical renal risk. With that said, when in doubt, always have a shared decision-making discussion with your patients and be up front about the potential risks and benefits based on the available evidence.
Source
The dose of iodinated contrast required for a CT scan is below the toxicological threshold of concern for nephrotoxicity: a toxicological perspective. JEM Rep. 2026 Jun;5(2). doi: 10.1016/j.jemrpt.2026.100220.
