The role of iodine in hypersensitivity reactions to radio contrast media
Article first published online: 3 NOV 2009
© 2009 Blackwell Publishing Ltd
Clinical & Experimental Allergy
Volume 40, Issue 3, pages 468–475, March 2010
How to Cite
Scherer, K., Harr, T., Bach, S. and Bircher, A. J. (2010), The role of iodine in hypersensitivity reactions to radio contrast media. Clinical & Experimental Allergy, 40: 468–475. doi: 10.1111/j.1365-2222.2009.03361.x
- Issue published online: 8 FEB 2010
- Article first published online: 3 NOV 2009
- Submitted 16 August 2008; revised 14 August 2009; accepted 17 August 2009
- Lugol's solution;
- provocation test;
- radio contrast media
Introduction Hypersensitivity reactions to iodinated radio contrast media (RCM) are either immediate-type (IT) or delayed reactions (DT). In IT, the pathomechanism is unclear. In DT, delayed positive patch (PT) and intradermal tests (IDT) and RCM-specific T cells suggest a T cell-mediated mechanism. In both, the role of iodine has not been clarified; however, patients are often labelled as ‘iodine allergic’. Occasionally, positive skin tests to iodine-containing drugs are observed.
Objective We investigated the presence of hypersensitivity to iodine in patients with a history of hypersensitivity reactions to RCM.
Methods Nineteen patients with a history of IT (n=9) or DT (n=10) to RCM were investigated. Skin prick tests, IDT and PT with several RCM and iodine formulations were carried out. All underwent oral provocation with Lugol's solution (LS). Two patients each with iodine mumps, contact dermatitis to iodized antiseptics and chronic idiopathic urticaria served as control or proof of concept.
Results In the IT group, skin tests were positive in three out of nine patients to one RCM. One patient with negative skin tests reacted twice to oral iodine with urticaria. In the DT group, sensitization to one or several RCM was identified in 10 out of 10 patients. In seven out of 10 patients, additional sensitizations to the iodine formulations were found. Two patients developed a mild exanthema after oral provocation with LS.
Conclusion We have previously demonstrated in patients with iodine mumps that an oral challenge with LS is a valid means to elicit hypersensitivity reactions to iodine. In 19 patients, we showed that iodine is rarely the eliciting agent in hypersensitivity reactions to RCM. Only one patient with a late urticaria to an RCM with a late urticaria to LS and two patients with DT and broad sensitization to all RCM tested reacted to LS with an exanthema. In most cases, more likely the RCM molecules and not iodine are the eliciting compounds.
Cite this as: K. Scherer, T. Harr, S. Bach and A. J. Bircher, Clinical & Experimental Allergy, 2010 (40) 468–475.