Answer to Question #9026 Submitted to "Ask the Experts"

Category: Nuclear Medicine Patient Issues — Therapeutic Nuclear Medicine

The following question was answered by an expert in the appropriate field:

Q

I just recently had an iodine radiation treatment and a lot of people have been telling me after having it that I can't conceive any more children. I'm only 21. I also have been traveling a lot and was told I wouldn't get through security screening at the airport easily, if even at all, because the radiation will make the metal detectors go off.

A

I'm sorry that you're getting such scary information from nonexperts. Ideally, your physician should have fielded these questions for you. I am a nuclear medicine physician and a radiation biologist and I will try to get you the answers you need, but I have very little information from you to go on right now.

The doses of iodine-131-sodium iodide are very different depending on whether you were treated for hyperthyroidism or thyroid cancer and so is the time the radioactive material stays in your body. With hyperthyroidism you generally get a relatively low dose, but it stays around for weeks. With thyroid cancer, you get a relatively high dose but it leaves your body quickly, most of it going out in urine in a matter of a few days.

In terms of your pregnancy question, you certainly can safely have children. I generally recommend that patients with hyperthyroidism wait four months after treatment because they might need a second treatment and can't get it if they are pregnant. A second treatment is generally administered at about four months after the first one. If you were treated for thyroid cancer, I recommend that you wait about a month after treatment; theoretically that allows for radiation repair in your eggs, and most of the radioactive iodine is long gone. So, no matter which disease you have and no matter what the administered dose, you can safely have children.

As far as travel is concerned, radioactive iodine does not trigger metal detectors, ever. Iodine is not a metal. There are, however, some airports that scan passengers for radioactive material. You can trigger the detector system, so you need a card from your physician telling the Transportation Security Administration (TSA) people what radionuclide and radiopharmaceutical you received (that is, iodine-131-sodium iodide), what the dose was, the date of administration, and the person to call for any safety-related information. If you were treated with iodine-131 for hyperthyroidism, the length of time you will have to wait after treatment for safe airline travel depends upon the dose, the amount your thyroid takes up, and the speed at which the radioactive iodine leaves your body. Generally speaking, even if you trigger the detectors (it takes a minuscule amount to trigger the detectors), it would be safe for you to travel within a few days to a week. If you were treated with iodine-131 for thyroid cancer, it would generally be safe for you to travel within a few days to perhaps a week. You have a right to insist upon an information card from your physician to show to the TSA people (and any foreign equivalents).

Carol S. Marcus, PhD, MD
Professor of Radiation Oncology and of Radiological Sciences, UCLA

Ask the Experts is posting answers using only SI (the International System of Units) in accordance with international practice. To convert these to traditional units we have prepared a conversion table. You can also view a diagram to help put the radiation information presented in this question and answer in perspective. Explanations of radiation terms can be found here.
Answer posted on 4 May 2010. The information posted on this web page is intended as general reference information only. Specific facts and circumstances may affect the applicability of concepts, materials, and information described herein. The information provided is not a substitute for professional advice and should not be relied upon in the absence of such professional advice. To the best of our knowledge, answers are correct at the time they are posted. Be advised that over time, requirements could change, new data could be made available, and Internet links could change, affecting the correctness of the answers. Answers are the professional opinions of the expert responding to each question; they do not necessarily represent the position of the Health Physics Society.