Skip to content
  • About
  • Contact
  • Contribute
  • Book
  • Careers
  • Podcast
  • Recommended
  • Speaking
  • All
  • Physician
  • Practice
  • Policy
  • Finance
  • Conditions
  • .edu
  • Patient
  • Meds
  • Tech
  • Social
  • Video
    • All
    • Physician
    • Practice
    • Policy
    • Finance
    • Conditions
    • .edu
    • Patient
    • Meds
    • Tech
    • Social
    • Video
    • About
    • Contact
    • Contribute
    • Book
    • Careers
    • Podcast
    • Recommended
    • Speaking

I have a shellfish allergy. Can I have contrast?

Jennifer Gunter, MD
Conditions
December 2, 2013
337 Shares
Share
Tweet
Share

I hear it over and over again.

From a nurse, “She can’t have providine prep, she has a shellfish allergy.”

From the patient, “I can’t have the contrast because I’m allergic to iodine and shellfish.”

The list of allergies placed in the chart by a doctor, “Radiocontrast. Iodine. Shellfish.”

It’s not the fault of the patients who are typically repeating the medical misinformation they have been given. However, the medical professionals who perpetuate the iodine-shellfish-radiocontrast allergy drive me batty because they either don’t understand the medicine involved or understand there is no link but don’t take the time to educate the patient and correct the chart.

In short, I hate medical myths. Undoing what someone once said to somebody is hard because when someone has believed something for so long (whether they are a doctor, nurse, or patient) they are not always open to a change. I estimate that it takes a minimum of three conversations to under one incorrect piece of information.

Let’s break it down.

While shellfish allergy is a very real allergy and potentially life threatening, it is not an iodine allergy. The major allergens in shellfish are tropomyosins, which are proteins is the muscle and definitely not iodine. Tropomyosins cross react among various shellfish, but not scaled fish so that is why you can be allergic to crab and eat salmon. People who are allergic to scaled fish are typically allergic to a different muscle protein, parvalbumin.

Iodine is not an allergen. We all have iodine in our bodies. It is in our thyroid hormones and in amino acids. We would die without iodine. Iodine deficiency is such a potential health problem that most table salt in the United States contains iodine. Listing iodine as an allergen in the chart is wrong. It is worth repeating, iodine cannot be an allergen.

People can have reactions to providone-iodine prep (which contains iodine), but this is due to allergens in the solution not the iodine. If someone has a reaction to providone-iodine prep the prep should be listed as the allergen, not the iodine. It’s an important distinction. With many products it’s the additives that drive an allergic reaction.

People can have severe reactions to radiocontrast, but these are not allergic reactions. Anaphylaxis is due to a the immune system producing IgE immunoglobulins in response to an allergen, such as the tropomyosin in shellfish. It is an allergic response. When a person is re-exposed, the allergen-IgE complex triggers the severe inflammatory cascade.

Reactions to radiocontrast are believed to be anaphylactoid and so are not caused by IgE. What’s the difference? Anaphylaxis requires IgE to trigger the inflammatory cascade and with an anaphylactoid reaction the substance directly stimulates the inflammatory cascade, no immune system intervention is needed. What causes triggers anaphylactoid reactions with radiocontrast? Not the iodine, but likely the hyperosmolarity because  hyperosmolar solutions are highly irritating. As expected, anaphylactoid reactions are much less frequent with the lower osmolar radiocontrast solutions more commonly used today.

As an aside, reactions to radiocontrast (especially the older, more hyperosmolar solutions) are increased about three-fold in people with allergies to milk, eggs, and chocolate which according to the American Academy of Asthma, Allergy, and Immunology indicates a, “general atopic disposition, rather than an iodine specific reaction.” Basically, people with food allergies have a twitchy inflammatory response system and are at higher risk for non-allergen driven reactions as well.

So let’s get rid of the medical mythology surrounding iodine, shellfish, and radiocontrast. When incorrect allergies are listed in the chart it breeds confusion and both patients and their providers need and deserve accurate health information.

Shellfish allergy isn’t iodine driven.

Iodine isn’t an allergen.

Reactions to radiocontrast  are not an allergic reaction to iodine and are unlikely to be allergic reactions at all, but rather an inflammatory response to irritating hyperosmolar agents.

The science matters.

Jennifer Gunter is an obstetrician-gynecologist and author of The Preemie Primer. She blogs at her self-titled site, Dr. Jen Gunter.

Prev

Do safety net hospitals get penalized under new payment models?

December 2, 2013 Kevin 2
…
Next

Using simulated patients in medical education

December 2, 2013 Kevin 2
…

Tagged as: Radiology

Post navigation

< Previous Post
Do safety net hospitals get penalized under new payment models?
Next Post >
Using simulated patients in medical education

More by Jennifer Gunter, MD

  • The Ellen Show broadcasts potentially harmful information about ovarian cancer screening

    Jennifer Gunter, MD
  • Dear science: an appreciation

    Jennifer Gunter, MD
  • Are there too many female OB/GYNs?

    Jennifer Gunter, MD

More in Conditions

  • Overcoming the lies of depression: Senator John Fetterman’s struggle with mental health

    Harvey Max Chochinov, MD, PhD
  • Proposed USPSTF guideline update: Advocating for earlier breast cancer screening at age 40

    Hoag Memorial Hospital Presbyterian
  • The rising threat of lung cancer in Asian American female nonsmokers

    Alice S. Y. Lee, MD
  • Urgent innovation needed to address growing mental health crisis among children and families

    Monika Roots, MD
  • The importance of listening in health care: a mother’s journey advocating for children with chronic Lyme disease

    Cheryl Lazarus
  • The unjust reality of racial disparities in pediatric kidney transplants

    Lien Morcate
  • Most Popular

  • Past Week

    • Is chaos in health care leading us towards socialized medicine? How physician burnout is a catalyst.

      Howard Smith, MD | Physician
    • Boxing legends Tyson and Foreman: powerful lessons for a resilient and evolving health care future

      Harvey Castro, MD, MBA | Physician
    • A physician’s typical day, as envisioned by a non-clinician health care MBA: a satire

      Jennifer Lycette, MD | Physician
    • The tragic story of Mr. G: a painful journey towards understanding suicide

      William Lynes, MD | Physician
    • The rising threat of lung cancer in Asian American female nonsmokers

      Alice S. Y. Lee, MD | Conditions
    • Decoding name displays in health care: Privacy, identification, and compliance unveiled

      Deepak Gupta, MD | Physician
  • Past 6 Months

    • “Is your surgeon really skilled? The hidden threat to public safety in medicine.

      Gene Uzawa Dorio, MD | Physician
    • Revolutionize your practice: the value-based care model that reduces physician burnout

      Chandravadan Patel, MD | Physician
    • Breaking the cycle of racism in health care: a call for anti-racist action

      Tomi Mitchell, MD | Policy
    • Unveiling the hidden damage: the secretive world of medical boards

      Alan Lindemann, MD | Physician
    • An inspiring tribute to an exceptional radiologist who made a lasting impact

      Kim Downey, PT | Conditions
    • Proactive risk management: a game-changer in preventing physician burnout

      Howard Smith, MD | Physician
  • Recent Posts

    • A revolution in patient empowerment: Working together to save our medical system [PODCAST]

      The Podcast by KevinMD | Podcast
    • Revealing America’s expansion: the dark truth of Native American suffering and unjustified abuses

      Anonymous | Physician
    • Unlock financial freedom: The physician’s guide to lucrative multifamily syndications and wealth accumulation

      Pranay Parikh, MD | Finance
    • From Moscow Mule to the opioid crisis: Unveiling the tragic legacy and urgent solutions

      Osmund Agbo, MD | Meds
    • From journalism to medicine: Unveiling the untold stories of patients’ medical conditions

      Veronica Bonales, MD | Physician
    • Unlocking resilience: a powerful journey from trauma to transformation [PODCAST]

      The Podcast by KevinMD | Podcast

Subscribe to KevinMD and never miss a story!

Get free updates delivered free to your inbox.


Find jobs at
Careers by KevinMD.com

Search thousands of physician, PA, NP, and CRNA jobs now.

Learn more

View 13 Comments >

Founded in 2004 by Kevin Pho, MD, KevinMD.com is the web’s leading platform where physicians, advanced practitioners, nurses, medical students, and patients share their insight and tell their stories.

Social

  • Like on Facebook
  • Follow on Twitter
  • Connect on Linkedin
  • Subscribe on Youtube
  • Instagram

CME Spotlights

From MedPage Today

Latest News

  • New Antiviral Option for CMV Prophylaxis After Kidney Transplant
  • Infant RSV Vax Heads to FDA for Review
  • Is Getting Test Results Online Right Away a Good Idea? Yes, Patients Say
  • Residency Application System Cuts Section on Hobbies and Interests
  • Workplace Harassment, Cyber Incivility High for Minority Groups in Academic Medicine

Meeting Coverage

  • Phase II Study: Bispecific Oral Drug Tops Leading JAK Inhibitor for RA
  • Closing the Diversity Gaps in Urologic Oncology Leadership
  • Certain NSCLC Patients May Be Able to Stop Immunotherapy at 2 Years
  • No Survival Benefit With Immune Checkpoint Inhibitor Rechallenge in Metastatic RCC
  • Happy Sleep, Happy Couple?
  • Most Popular

  • Past Week

    • Is chaos in health care leading us towards socialized medicine? How physician burnout is a catalyst.

      Howard Smith, MD | Physician
    • Boxing legends Tyson and Foreman: powerful lessons for a resilient and evolving health care future

      Harvey Castro, MD, MBA | Physician
    • A physician’s typical day, as envisioned by a non-clinician health care MBA: a satire

      Jennifer Lycette, MD | Physician
    • The tragic story of Mr. G: a painful journey towards understanding suicide

      William Lynes, MD | Physician
    • The rising threat of lung cancer in Asian American female nonsmokers

      Alice S. Y. Lee, MD | Conditions
    • Decoding name displays in health care: Privacy, identification, and compliance unveiled

      Deepak Gupta, MD | Physician
  • Past 6 Months

    • “Is your surgeon really skilled? The hidden threat to public safety in medicine.

      Gene Uzawa Dorio, MD | Physician
    • Revolutionize your practice: the value-based care model that reduces physician burnout

      Chandravadan Patel, MD | Physician
    • Breaking the cycle of racism in health care: a call for anti-racist action

      Tomi Mitchell, MD | Policy
    • Unveiling the hidden damage: the secretive world of medical boards

      Alan Lindemann, MD | Physician
    • An inspiring tribute to an exceptional radiologist who made a lasting impact

      Kim Downey, PT | Conditions
    • Proactive risk management: a game-changer in preventing physician burnout

      Howard Smith, MD | Physician
  • Recent Posts

    • A revolution in patient empowerment: Working together to save our medical system [PODCAST]

      The Podcast by KevinMD | Podcast
    • Revealing America’s expansion: the dark truth of Native American suffering and unjustified abuses

      Anonymous | Physician
    • Unlock financial freedom: The physician’s guide to lucrative multifamily syndications and wealth accumulation

      Pranay Parikh, MD | Finance
    • From Moscow Mule to the opioid crisis: Unveiling the tragic legacy and urgent solutions

      Osmund Agbo, MD | Meds
    • From journalism to medicine: Unveiling the untold stories of patients’ medical conditions

      Veronica Bonales, MD | Physician
    • Unlocking resilience: a powerful journey from trauma to transformation [PODCAST]

      The Podcast by KevinMD | Podcast

MedPage Today Professional

An Everyday Health Property Medpage Today
  • Terms of Use | Disclaimer
  • Privacy Policy
  • DMCA Policy
All Content © KevinMD, LLC
Site by Outthink Group

I have a shellfish allergy. Can I have contrast?
13 comments

Comments are moderated before they are published. Please read the comment policy.

Loading Comments...