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Date of last update: 10/17/2017.

Forum Name: Endocrinology Topics

Question: Taking Radio Active Iodine When I am Allergic to Shellfish

 serdamitchel - Wed Nov 18, 2009 11:13 pm

I was recently diagnosed with hyperthyroidism. My T4 level was 523 in Sept. stable in Oct. and 650 something in November. I took the uptake with iodine with a prescription of pretizone and benedryl. I did not react. But, I am allergic and since I have had reactions before my doctor was warry of having me take the one time radiation pill because of the amount of iodine. So, she recommended surgery. I am terrified. I had a horrible time with the C-Section I had with my son who's going to be 4 soon. I also do not numb. The spinal they gave me did not work. I had to have a specialist flown in from Cleveland to put me out right before the c-section. And I did not numb when I had a wisedom tooth removed. They shoot me 6 times and I still felt it. I even passed out on my way to pay for the service because of the shock of feeling all that pain.
What are my options here? I want to have another baby as soon as I can. But I'm afraid the radiation will stop that from happening. And with the surgery, I have state issued medical insurance so it took two months to see an actual endocrinologist. I'm terrified they will get a regular surgeon and not a skilled neck and throat doctor to help me since my insurance isn't all that great. Please let me know. Any advice is appreciated!! Thank you
 Dr.M.Aroon kamath - Mon Jul 12, 2010 12:57 am

User avatar Hi,
Radioactive iodine (RAI) is unique in that it is taken up selectively by functioning thyroid tissue only.

Very small amounts of iodine uptake may transiently occur in the salivary glands, stomach, and ovaries/testicles.

Radioactive iodine may thus affect a woman's ovaries, and some women may have menstrual irregularities for up to an year after treatment. Many clinicians recommend that women should avoid pregnancy for 6 months to preferably an year following treatment. No ill effects have been observed in offspring of parents who received radioactive iodine in the past.

Miscarriage rates have been seen to increase(double) following RAI treatment.Some long term followup studies have shown that RAI did not appear to have an effect on subsequent pregnancies and offspring over a 10-year follow-up period after RAI. Miscarriage rates seemed to be non-dose dependent. There is also a possibility of slightly earlier age of menopause.

Many types of seafood may contain iodine. However, "IgE antibody mediated seafood allergy" has never been ascribed to iodine, but rather to certain specific proteins in fish and shellfish (e.g.,tropomyosin, parvalbumin). These proteins do not contain iodine. Thus, fish or shellfish allergy does not automatically mean a sensitivity/allergy to iodine.
(Sampson HA, Food allergy. J Allergy Clin Immunol. 2003 Feb;111(2 Suppl):S540-7).

Radiocontrast media (RCM) containing organic iodine may cause adverse reactions such as bronchospasm, laryngospasm, urticaria, angioedema, & shock. These reactions are "anaphylactoid" in nature and not IgE mediated. Higher osmolar radiocontrast agents seem to cause more reactions.Therefore these reactions lack any iodine-specific reactivity.

In your case,with this information on hand, you should discuss the pros and cons of surgery vs RAI treatment with your surgeon and take an informed decision.
Good luck!

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