IV dye or radiocontrast media has been utilized for various radiological studies such as CAT scans, angiograms and intravenous pyelograms. Generally, there are 2 forms of IV dye utilized for most radiological testing – ionic high-osmolality contrast media (HOCM) and the non-ionic low-osmolality contrast media (LOCM).
It is important to note that LOCM has been the chosen form of IV dye due to its proven and safety record but quite costly than HOCM.
Close look on IV dye allergy
The reactions to IV dye specifically ROCM is quite common which occurs to 5-8% of individuals receiving the IV dye. Most of the reactions are minor and include nausea, vomiting and a warm sensation.
Essentially, these symptoms manifest only for a limited period of time and do not need treatment. The moderate reactions include hives, swelling and severe vomiting which occur in 1% of those who receive the ROCM IV dye and require treatment. Cases of severe reactions or anaphylaxis are considered uncommon.
The reactions to LOCM are relatively lower although reactions are severe and often includes death. The reactions to ROCM IV dyes are not actually allergic in nature. This simply means that there is no allergic antibody involved that triggers the reaction. It acts directly to release histamine and other chemicals from the mast cells.
Who are at risk?
Individuals who are at high risk for reactions to IV dye include the following:
- Individuals who had previous reactions to ROCM IV dye
- Those who have history of allergies
- Asthmatic individuals
- History of heart and kidney disease
- Individuals using beta-blockers
Despite the widespread myth, those who have shellfish or seafood allergy are not at risk for developing a reaction to IV dyes. It is important to note that shellfish allergy is connected to the protein content of these foods, not the iodine content. Additionally, those who are allergic to topical iodine cleaners are not at risk for reactions.
It is sad to note that there is no test available to diagnose IV dye allergy. Both skin tests and RAST are not effective in providing a diagnosis. A diagnosis is usually made only after the symptoms occurred. Otherwise, it is only possible to determine that an individual is at high risk for a reaction based on the given risk factors.
The treatment for an acute reaction to IV dye is similar to anaphylaxis. The treatment includes injectable epinephrine and antihistamines as well as the administration of intravenous fluids for low blood pressure and shock. The preventive measures for future reactions must include the following:
- Consult the doctor regarding the risks and benefits of performing a test with IV dye and other possible alternatives
- Using medications before the administration of ROCM to prevent or minimize the risk for reactions such as prednisone or diphenhydramine