Gadolinium Based Contrast Agents
How the FDA Protects Against Side Effects of Gadolinium
Since the discovery of the link between nephrogenic systemic fibrosis and gadolinium based contrast agents, the FDA have investigated the issue ever since, as well as impose regulations of manufactured contrast dyes to follow to reduce gadolinium side effects as much as possible.
The FDA has mandated that all manufacturers add a boxed warning and a new “Warnings” label to describe the risks of use. Currently, there are 5 gadolinium agents that are approved by the FDA:
- Magnevist
- MultiHance
- Omniscan
- OptiMARK
- ProHance
Contrast agents can be used for MRI and MRA scans. MRI machines (magnetic resonance imaging) are used for getting detailed images of the organs and soft tissue in the body. An MRA (magnetic resonance angiography) scan is a specialized type of MRI, which is designed to capture blood vessels and arteries instead. They are mostly used to detect diseases caused by affected blood vessels, such as aneurysms and atherosclerosis disease.
When it comes to FDA regulations, the two types of scans are completely different. The five contrast agents listed above are only approved by the FDA for MRI scans. They are not approved for MRA scans. In fact, there are NO FDA APPROVED CONTRAST AGENTS FOR MAGNETIC RESONANCE ANGIOGRAPHIES. This is important to note, as there are doctors who will still use gadolinium based contrast agents for MRAs because it improves the quality of the results.
There exist other types of contrast dyes that do not contain gadolinium. There are two that are approved by the FDA – Feridex I.V., which is iron based, and Teslascan, which is manganese based. Being as how these two are only allowed for detecting lesions of the liver, they are not viable alternatives. Only the list above is for general MRI scans, and therefore, the possibility of gadolinium side effects still exists.
To learn more about the specific regulations and guidelines imposed by the FDA regarding gadolinium based contrast agents, check out the FDA website regarding MRI contrast agents.
Gadolinium Side Effects
When undergoing an MRI scan, your doctor may use a gadolinium contrast dye to improve the quality of the results. Generally, the contrast dye is safe to use, which will pass through and exit the body naturally with time. However, there may be side effects which can possibly have severe and fatal outcomes under some circumstances.
Some minor gadolinium side effects include headaches, nausea, light headedness, and a decrease in blood pressure. These should not be a cause for concern. The sudden onsets of these symptoms are most likely just a result of increased anxiety of having the scan or being injected with the contrast dye. They should go away shortly after the scan. Be sure to take it easy if you are feeling uncomfortable and uneasy after your scan.
Other known side effects are a result of an allergic reaction to gadolinium. Complications are usually mild, such as sweating, skin rashes, itching and hives. Potentially fatal complications include irritation of the blood vessels and blood clots.
When people think of severe gadolinium side effects, nephrogenic systemic fibrosis (NSF) is what comes to mind. NSF is a fatal syndrome that results in the fibrosis of soft and connective tissue. This includes the joints, skin and internal organs. The most noticeable effect is that the skin will tighten and harden and the joints will stiffen up, making it harder and more painful to stretch and move parts of the body. It is much easier to develop in patients with a history of renal (kidney) disease and failure.
Nephrogenic systemic fibrosis is a relatively new disease. The first case was reported in 1997, with the first study being published almost 3 years later. It was not until 2006 that gadolinium based contrast agents were linked to nephrogenic systemic fibrosis. Not much is known about how exactly this syndrome emerges, and there is no known treatment option as of today.
It is imperative that patients make it known to their doctors and nurses about their history of kidney complications if there were any. If there is only evidence of slight kidney impairment, contrast dyes may still be used if deemed essential, but it is very important that the proposed guidelines for use are strictly adhered to. It is highly recommended that all patients undergoing their first MRI scan be screened for kidney disease beforehand to avoid all fatal gadolinium side effects.
Why Are Gadolinium Based Contrast Agents Used?
MRI scans (and MRA scans) are known to produce very detailed images of the inner workings of the body. They are used extensively in the medical field to detect and diagnose many health conditions that could not be found otherwise. However, there are some cases where it is advantageous to use a gadolinium based contrast agent to enhance the quality of the scanned images or to better detect foreign growths inside the body.
Gadolinium is a rare earth lanthanide metal. In its original form, it is a silvery white, malleable and ductile metal. As a free ion, it is a highly toxic element to humans. It must go through a process known as chelation before it can be utilized in practical applications. Chelation is the process of taking a free ion and adding bonds with other organic compounds to prevent it from freely and uncontrollably reacting with other elements and compounds that could have detrimental effects.
The reason gadolinium has found its way into MRI scan applications is because of its strong paramagnetic properties. A paramagnetic metal does not exhibit any magnetic effects in its original state. When placed in an externally applied magnetic field, it will align its molecules parallel to the it, and in turn, create its own magnetic field. They are easily detectable in a strong external magnetic field (such as that produced by an MRI machine), allowing the possibility for much more detailed scans.
Gadolinium based contrast dyes have been manufactured to be safe for the patient and they follow strict FDA regulations to avoid any health complications. However, there are still gadolinium side effects that people must be completely aware of to avoid the risk of harm to themselves.
