I read with interest the Florida case with the $4.7 million verdict (Iodine contrast media kills man with known shellfish allergy, What’s the Verdict? J Fam Pract. 2010;59:244). As a dermatologist who deals with many allergy issues, I was surprised that the verdict was based on the “supposed” cross-reaction of a shellfish allergy with contrast iodine material. Unfortunately, this is a medical myth that has been propagated for many years.
An excellent review on this subject recently appeared in the Journal of Emergency Medicine.1 The authors surveyed 231 physicians at 6 academic medical centers and found that 89% of cardiologists and two-thirds of radiologists routinely ask their patients if they are allergic to shellfish before administering an iodinated contrast agent. They also noted that 35% of radiologists and 50% of cardiologists would withhold radiocontrast or premedicate patients with shellfish allergies.
When an individual has a seafood or shellfish allergy, it is the protein in the animal that the individual is allergic to. The allergens from fish and shellfish are actually 2 different types of proteins, and have absolutely nothing to do with iodine. Iodine is an essential element that is found throughout the body and is essential to the production of thyroid hormone and various amino acids in the body. One could not survive without iodine. It is, therefore, impossible to have a true allergy to iodine. Although an individual could react to the various allergens contained in iodine skin preps, it is not the iodine that is causing the allergy.
It is the general opinion of experts in the fields of radiology and allergy/immunology that any “allergic” individual has a 3-fold increase in the likelihood of an allergic reaction to radiocontrast material, and more than 55% of individuals have at least 1 or 2 allergies. It is not reasonable to withhold needed treatment, whether it be contrast dye, anesthesia, or any medication, for fear of a potential reaction—particularly in an emergency like the case in question, in which the procedure was done in an attempt to save the life of a 41-year-old patient. The risk of dying from cardiac arrest is great, while the risk of death from contrast dye is miniscule.
Propagating the myth of the seafood-iodine-contrast material connection not only disseminates misinformation, but also breeds multimillion dollar lawsuits.
Melinda F. Greenfield, DO
Albany, Ga