Seafood, iodine, CAT scans and allergic reactions

Seafood and iodine: an analysis of a medical myth.
Huang SW.
Department of Pediatrics, University of Florida College of Medicine, Gainesville, Florida 32610, USA.

There is a prevailing myth that iodine levels in seafood and seafood allergy are connected.

Therefore, we designed a study to collect information about this misconception from patients referred to our pediatric allergy clinic because of suspected seafood allergy.

We presented five questions to our patients, and the most surprising result was that the majority of them believe that iodine is linked to seafood allergy.

As a result, many felt uneasy about the use of iodine radiocontrast media (CAT scans). A survey of iodine content in common foods showed that, although the iodine content of seafood is higher than non-seafood items, daily consumption of the latter is much greater and, therefore, any phobia about iodine in seafood is unfounded.

We encourage strong public education about seafood allergy by allergy specialists.

Allergy Asthma Proc. 2005 Nov-Dec;26(6):468-9.

Seafood allergy and radiocontrast media: are physicians propagating a myth?
Beaty AD, Lieberman PL, Slavin RG.
Section of Allergy and Clinical Immunology, Division of Immunobiology, Department of Internal Medicine, Saint Louis University School of Medicine, St Louis, MO 63104, USA.

Recent surveys have indicated that the misconception that seafood allergy confers a disproportionately increased risk of adverse reactions to radiocontrast media remains pervasive among physicians and patients. One possible explanation for the persistence of this notion is that physicians responsible for radiocontrast administration are inadvertently contributing to its propagation.

An anonymous survey was sent to 231 faculty radiologist and interventional cardiologists at 6 Midwest academic medical centers. Two questions dealt directly with seafood allergy related to radiocontrast media administration, and 6 questions served as distracters.

Sixty-nine percent of responders indicated that they inquire about a history of seafood allergy before radiocontrast media administration. Some 37.2% of responders replied that they would withhold radiocontrast media or recommend premedication on the basis of a history of seafood allergy.

Even among faculty physicians at university medical centers, the notion of seafood allergy as a significant risk factor for adverse radiocontrast media reactions remains pervasive. Even if no action is taken on the basis of the answer, it seems probable that the act of inquiring about seafood allergy before radiocontrast media administration could lead patients and trainees to presume an inherent risk in patients who are seafood allergic, thus propagating the notion. Physician education with respect to seafood allergy and radiocontrast media administration is vital to halting the persistence of this misconception.

Am J Med. 2008 Aug;121(8):e19.

In reality, the general risk of an adverse reaction to a contrast agent (CAT scan) ranges from 0.2 percent to 17 percent (depending on several factors), with severe reactions extremely rare.

Courtesy of the NY Times - Health


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