Sixty-nine percent of faculty radiologist and interventional cardiologists at 6 Midwest academic medical centers responded that they inquire about a history of seafood allergy before radiocontrast media administration.37.2% replied that they would withhold radiocontrast media or recommend premedication on the basis of a history of seafood allergy.
The rate of adverse events from radiocontrast media administration at 5-12% for high-osmolality contrast media and 1-4% for low-osmolality contrast media.
Immediate-type adverse reactions to radiocontrast media are virtually always non-IgE mediated and have thus been previously termed “anaphylactoid reactions.” It was recently recommended that the term “nonimmunologic anaphylaxis” be used instead.
Patients with allergy to seafood and shellfish have specific IgE against proteins within the meat of the fish, and that iodine content plays no etiologic role. Radiocontrast media reactions are almost always non-IgE mediated and the the idea of cross-reactivity between iodine and radiocontrast media has been discounted.
Mind map diagram of adverse reactions to drugs.
See a related clinical case: Anaphylactoid Reaction to Intravenous Contrast from AllergyCases.org.
Dr Lockey: Radiocontrast Reactions: Rectifying Misconceptions About Shellfish Allergy and Iodine http://buff.ly/1iZE6WF
References:
Seafood Allergy and Radiocontrast Media: Are Physicians Propagating a Myth? Andrew D. Beaty, MD, Philip L. Lieberman, MD, Raymond G. Slavin, MD. American Journal of Medicine,Volume 121, Issue 2, Pages 158.e1-158.e4 (February 2008).
'Iodine allergy' label is misleading - Australian Prescriber http://goo.gl/C4zQ
AAAAI explains why there is no IgE antibody-mediated "iodine allergy." IgE mediated seafood allergy has never been attributed to iodine, but rather to specific proteins in fish and shellfish http://is.gd/1oRpX
50% of hypersensitivity reactions to contrast media may be caused by an immunological mechanism. Allergy, 2009.
3% of patients who are exposed to iodinated contrast media develop delayed hypersensitivity reactions. Skin prick test is negative but the patch test is positive. Medscape and JACI, 2011.
Image source: Wikipedia, GNU Free Documentation License and public domain.
3% of patients who are exposed to iodinated contrast media develop delayed hypersensitivity reactions. Skin prick test is negative but the patch test is positive. Medscape and JACI, 2011.
Image source: Wikipedia, GNU Free Documentation License and public domain.