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.

References