2022 Volume 21 Issue 4 Pages 276-282
A 75-year-old male developed anaphylactic shock after administration of the CT contrast agent iopamidol (Oypalomin ○R ) and was hospitalized to our hospital. Immediate-type reactions after intravascular injection of iodinated radiocontrast media were considered to be non-allergic mechanisms such as the direct histamine-releasing effects of iodinated radiocontrast media and nonspecific complement activation. However, increasing evidence suggests that there is a drugspecific true IgE-mediated allergy among the immediate reactions, and it can be differentiated from non-allergic reactions using skin tests. We have developed an iodinated radiocontrast media allergy test protocol based on previous publications that reported how to identify the allergic reactions. According to the protocol, we performed an intradermal test of a 10-fold diluted solution of iopamidol in a patient. The immediate reaction of the intradermal test of iopamidol was positive, whereas the intradermal test for all other iodine contrast media was negative. The patient was diagnosed with immediate allergy to iopamidol. As iohexol had a negative intradermal test and showed no symptoms in the intravenous test, it could be used as an alternative drug. Although the mechanism of the iodine contrast medium allergy is unclear, devising such a protocol is useful for differentiating allergic reactions with iodine contrast media. It will be very useful for patients to find alternative contrast media that can be used in the future. We will continue to use this protocol and improve it. Skin Research, 21 : 276-282, 2022
