CT contrast dye and your kidneys: how worried should you be?
Dr. Joan J. Morales Lappot, MD3 min read · Leer en español
In briefMany patients are told to "be careful with dye" and then worry about getting a scan they truly need. The risk from modern CT contrast is lower than once thought, but it is not zero for everyone.
What has changed
Older studies blamed contrast for many kidney injuries that were actually caused by the illness that led to the scan. Newer research suggests that for most people, including many with mild or moderate CKD, today's iodine-based contrast carries little risk. The concern is greatest when the eGFR is below about 30 or when kidney function is already dropping.
If you are at higher risk
- Tell the imaging team about your kidney disease and send recent labs
- Ask whether the scan can be done without contrast or with another test
- Get IV fluids before and after if your doctor recommends them
- Your doctor may hold certain medicines, such as metformin, NSAIDs or water pills, around the time of the scan
- Recheck creatinine a few days later if you are high risk
MRI contrast is different
MRI uses gadolinium rather than iodine. Newer gadolinium agents are considered low risk, but people on dialysis or with very low kidney function should still let the team know, so they choose the safest agent.