Many patients report an allergy to iodinated RCM, sometimes adding to the complexity of diagnostic decision making. Here are a few pearls to help:
- Seafood or shellfish allergy is NOT a risk factor for IHR to RCM
- Iodine and iodide are small molecules that do NOT cause anaphylactic or anaphylactoid reactions
- Life-threatening reactions occur in only 0.004 to 0.04 percent of nonionic low osmolality RCM infusions
- Our radiology department uses primarily iohexol (Omnipaque) for IV contrast with a low osmolality of 844
- Iodixanol (Visipaque) is the iso-osmotic alternative with an osmolality of 290
Bottom line: Despite the lack of cross reactivity with shellfish/iodine allergies AND the very low risk associated with today’s low osmolality agents, premedication is still indicated in patient’s with a history of IHR to RCM.