Why gadolinium in MRI contrast dye is safe
In November 2017, martial arts expert and actor Chuck Norris filed a lawsuit in California alleging an ingredient in a contrast dye used in a specific type of magnetic resonance imaging (MRI) poisoned his wife, resulting in extreme illness and a mountain of healthcare bills.
This allegation is striking fear in individuals who need MRIs for ongoing care or diagnosis. There are a few key facts to address upfront:
- Millions of people have received gadolinium-based contrast agents, or GBCAs, for several decades without harm
- Older versions of gadolinium-containing dyes, called linear agents, are less often used today in favor of lower-dose, safer versions called macrocyclic agents
- The individuals who do get gadolinium-based MRI contrast dye need it, as the dye is extremely effective for detecting cancerous masses that can be hidden without the contrast dye
Let’s walk through each of these facts to clarify the safety and effectiveness of gadolinium, who needs it and what precautions we take to ensure patients’ safety when receiving MRIs.
Gadolinium has a long track record of safety
After gadolinium is administered, the body removes it through the kidneys, as it does most other medications. Recent studies in people and animals have confirmed that, even in individuals with normal kidney function, small amounts of gadolinium can still remain in the brain and body long-term. However, a small amount of gadolinium doesn’t put patients at risk.
Gadolinium is extremely safe, with serious adverse reactions occurring in roughly 0.03 percent of all doses. As researchers noted in studies from 2008 and 2015 of patients exposed to gadolinium over time, those who were neither pregnant nor in kidney failure have rarely experienced side effects. In fact, fewer than 50 patients in the 30-year, 30 million-dose history complained of long-lasting side effects (such as headaches, brain fog and skin plaques).
It is also important to note that, for privacy, these patients’ records did not reveal the reasons for their MRIs, so a definitive link to gadolinium for these effects was never established. Still, in this large population pool, fewer than 50 patients out of 30 million doses is a staggeringly low number—roughly on par with the 1-in-700,000 chance any random American has of getting struck by lightning in a given year.
According to the Food and Drug Administration (FDA), the only scientifically established adverse health effect related to gadolinium is a rare condition called nephrogenic systemic fibrosis, or NSF, a painful disease of the skin. NSF can occur in a small subgroup of patients with pre-existing kidney failure. These patients, especially in the early 1980s and ’90s, received high doses of the earliest linear gadolinium.
A typical dose today is about 7 to 15 cc (cubic centimeters), which is less than a shot glass. But, 25 to 30 years ago, a typical dose was five or six times that amount, and the agent was less safe than it is today. For patients who were on dialysis or required a kidney transplant due to kidney failure, this was too much for their damaged kidneys to filter out. About a thousand patients worldwide developed NSF. A small portion of these patients died, and because of this, there were some changes made in the protocols used for gadolinium administration.
Newer forms of GBCAs are much safer
The first protocol set in place to protect patients from further developing NSF was highly effective. Patients with kidney failure were no longer given GBCAs unless it was medically unavoidable. All patients set to receive an MRI first were screened for kidney function. Those with kidney disease, even if found to be mild cases, were not given gadolinium.
Following the adoption of these guidelines in 2007, a study was conducted to search electronic medical records based on the criteria set forth to establish a trend in new NSF cases. In the three years following the restrictive GBCA guidelines adoption, no new cases of NSF were identified in a pool of nearly 53,000 contrast-enhanced MRIs, 36 of which were performed in patients considered to have kidney disease.
Another important feature of the gadolinium used today lies in its molecular structure. Many of the patients who developed NSF in the ’80s and ’90s likely were given higher doses of gadolinium, as mentioned, but it was also a less-stable, linear-structured agent. Linear GBCAs stay in the body longer than low-dose macrocyclic GBCAs that are used today, and the body can get rid of macrocyclic GBCAs more easily than the linear dyes.
Only people who really need gadolinium-based MRI contrast receive it
These MRI scans find things that we would not be able to detect otherwise. They are used to detect flares of multiple sclerosis (MS) in the brain, subtle brain tumors, cancer that has spread and other conditions that don’t show up on normal MRI scans. We really can’t do a breast MRI for early breast cancer without the contrast dye. If it were my wife or child having an MRI, I wouldn’t for a millisecond want them to go without gadolinium-based contrast dye, if I thought it would help their doctor detect cancer sooner.
It’s natural to have concerns about any medication your doctor prescribes, especially after it shows up in the news. Make sure you ask about any test your doctor recommends or performs, including any risks it may have and why you need it. We’ll take time to answer your questions and address any concerns you may have ahead of time.
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