Contrast Dye and the Kidneys

Contrast dye is a substance used in medical imaging tests. Contrast dye is a valuable tool, but it can impact the kidneys. Learn more in this article about why contrast dye is used and how it can affect the kidneys.¹

Why is contrast dye used?

Contrast dye is used in some imaging tests because it gives doctors a more detailed view of structures inside the body.¹

Images studies that require contrast dye include:²

• X-rays
• Computed tomography (CT) scans
• MRIs
• Angiography

Different types of contrast dye are used for various procedures. The most common dyes contain iodine or gadolinium. Modern contrast dyes are safer for the kidneys than those used in the past.^1,2

Can contrast dye affect the kidneys?

The medical term for kidney injury that occurs shortly after the use of iodine contrast is contrast-induced acute kidney injury (CI-AKI). An older term for the condition was contrast-induced nephropathy.²

Kidney damage that occurs after an MRI using gadolinium is called nephrogenic systemic fibrosis. This type of damage is much rarer now because of:²

• Safer forms of gadolinium contrast agents
• Stricter guidelines about when to use these agents

How is kidney injury after contrast diagnosed?

The change in kidney function seen with CI-AKI is often temporary. If CI-AKI develops, it usually starts within 48 hours of a test using iodine contrast.²

CI-AKI is linked to higher levels of creatinine in the body. Measuring creatinine helps doctors evaluate kidney function. In a person with CI-AKI, creatinine increases for 3 to 5 days. It is usually back to baseline in 7 to 10 days.²

Symptoms of CI-AKI can include:¹

• Feeling tired
• Poor appetite
• Swelling in the feet and ankles
• Puffiness around the eyes
• Dry and itchy skin

Who is at risk of kidney injury after contrast dye?

Risk factors for kidney injury linked to contrast dye include:²

• Chronic kidney disease or acute kidney injury
• Use of drugs known to cause kidney injury
• Diabetes
• Protein in the urine
• Dehydration
• Heart failure
• Higher amounts or repeated doses of contrast dye

Estimated glomerular filtration rate (eGFR) is a lab test that measures kidney function. People with lower eGFR are at higher risk of kidney injury after contrast dye. One study looked at people with a lower eGFR (less than 30) and found:^2,3

• 35 percent developed CI-AKI following a CT scan using iodine contrast
• 14 percent developed CI-AKI following CT scans without contrast

Researchers are questioning how much contrast dye contributes to kidney injury. Some experts have suggested that CI-AKI could be related to other factors.³

Other factors that may contribute to kidney injury after contrast exposure include:³

• Dehydration
• Infection
• Heart and blood vessel disease
• Heart failure
• Low blood pressure

Can kidney damage from contrast dye be prevented?

Doctors use several strategies to reduce the risk of kidney injury in people at high risk:²

• Intravenous (into a vein or IV) saline given before and during procedures requiring contrast
• Using the smallest dose of contrast dye possible
• Avoiding other drugs that could harm the kidneys
• Considering a different imaging study without contrast dye if possible

There are steps you can take to reduce your risk of kidney injury:¹

• Know your eGFR.
• Talk to your doctor about your kidney function before having imaging studies.
• Ask if you need contrast.
• If your eGFR is less than 30 and you need contrast, ask if there is an alternative test.