This is a myth!!! Shellfish allergy is an allergic reaction to a protein contained in the shellfish and not iodine. There is no such thing as an iodine allergy which is an essential mineral contained in our own thyroid hormones. In the 1920s, the U.S "iodized" salt to prevent iodine deficiencies which can result in goiter and cognitive difficulties.
While shellfish (shrimp, etc.) do contain ample amounts of iodine, there are many foods we eat daily that contain high levels of iodine as well. For those of you who suffer from a shellfish allergy, there is no increased risk in obtaining an imaging study containing IV contrast media. Patients who have had reactions to radiocontrast media, there is no increase for a shellfish allergy.