Can CT Scans Affect Your Thyroid? CT Contrast Side Effects

Photo by Edusoft @Pixabay

My Experience with CT Scan and Thyroid Issues

Can CT scans affect your thyroid? This is not a question I would have given any thought to until recently. I had gone to my doctor because of some sharp abdominal pains that I had been having for a couple of days. My doctor suspected that I had appendicitis so I was whisked away to the emergency department for possible emergency appendectomy. Once the emergency doctors saw me, they advised that I have a CT scan of the abdomen and pelvis as soon as possible. After being administered some intravenous contrast dye, I subsequently had the CT performed. When the contrast was being injected into my veins, I could feel my heart begin to beat faster and my throat got a strange hot feeling that moved down my chest and then disappeared. I had been warned that this was how I would feel, so I got comfortable and went through with the CT thyroid scan.

The radiologist who looked at the CT images asked for repeated images in order to get a better look at the urinary tract to rule out any problems with the bladder or kidneys. Fortunately, nothing showed up to be abnormal, and I was told that only the urine test had come back with signs of a UTI (urinary tract infection).

Follow-up Tests Show a Problem

A few weeks later, I was contacted by the Nuclear Medicine department to schedule me for a radioactive iodine scan of the thyroid because my thyroid function blood tests were abnormal. The endocrinologist had set up the scan to find out if my thyroid was functioning properly.

Now, I am not one to take too many medications and I always ask questions about my treatments. Before going through with the nuclear medicine scan, I read about the link between CT scans and abnormal thyroid levels. I found out a lot of information, which I want to share here.

Test Results

thyroid tests #1
Thyroid tests, photo by author

How did I know my thyroid was abnormal? First of all, my doctor had ordered a thyroid panel of blood tests: a TSH (thyroid stimulating hormone) and a free T4. At first the free T4 was a little high. The TSH, however, had dropped since the 2011 levels, to 0.04 (normal > 0.10). At the same time, my weight jumped up 10 pounds practically overnight, even though I had been good about avoiding gluten, and now I was even heavier than before I stopped eating wheat gluten!

I also started to notice that I was always tired, even after a good night’s sleep and in spite of taking my usual multivitamin every night. Apparently, these are some classic signs of thyroid dysfunction.


Hyper- vs. Hypothyroidism

According to the blood tests, which showed a low TSH and a mildly elevated free T4, I had begin manifesting hyperthyroid symptoms the month right after the CT scan. However, when I got repeat blood tests two months later in March, the opposite was true: the TSH was sky-high and the free T4 had dropped below normal. This was an indication of hypothyroidism, meaning that the thyroid was not producing thyroid hormone (measured by free T4) and so the pituitary gland was working overtime to produce TSH to stimulate thyroid hormone. This meant that the iodine from the CT scan had affected my thyroid so it couldn’t produce its own thyroid hormone!

Not wanting to add any more toxins to my system, I decided not to have the radioactive thyroid uptake scan. Besides, I had read that the iodine from the CT contrast would eventually clear from my system by itself. The nuclear medicine doctor agreed, canceled the scan, and said I could just wait and have another blood test in a month to monitor the thyroid function.

My reading shows the TSH has leveled off a bit and gone down slightly, though still abnormal at 30.6. The free T4 still has not recovered, at 0.6. The only changes I have made are to replace iodized with non-iodized salt in my diet, avoid shellfish (even though iodine content is minimal in seafood), and to drink distilled water rather than fluoridated tap water (even if it’s filtered, fluoride is nearly impossible to remove from water). I had been using a Brita filter, but now I always make an effort to only use distilled bottled water for drinking. I believed that distilled water would help clear toxins more quickly from the kidneys since there are less impurities for the kidneys to process. I have since found out that drinking only distilled water is NOT good for you and iodine can be good in some circumstances of hypothyroidism.


Related on Amazon

I am not a health professional, so I always advise that you contact your own medical practitioner to monitor your health. In addition, to provide more information on thyroid issues and thyroid health, below are some helpful resources available on Amazon.

 Living Well with Hypothyroidism: What Your Doctor Doesn’t Tell You… That You Need to Know (Revised Edition)Check Price Why Do I Still Have Thyroid Symptoms? when My Lab Tests Are Normal: a Revolutionary Breakthrough in Understanding Hashimoto’s Disease and HypothyroidismCheck Price Stop the Thyroid Madness: A Patient Revolution Against Decades of Inferior TreatmentCheck Price The Thyroid Solution Diet: Boost Your Sluggish Metabolism to Lose WeightCheck Price

Underactive Thyroid Problems: Is There a Solution?

thyroid disorders symptoms
Photo, Geralt @Pixabay

Synthetic vs. “Armour” Thyroid

Though this may be a long time before my thyroid normalizes, I have chosen not to go with the synthetic thyroid that the endocrinology doctor recommends. I inquired about the natural “Armour” thyroid but he replied that desiccated animal thyroid is not consistently manufactured and not shown to be effective in clinical trials. I understand his concern, because I have read that the T3 to T4 ratio is not always the same in these formulations, and too much T3 can result in hyperthyroidism, which is very difficult to control. I have heard so much bad about synthetic thyroid, however, that I can’t in good conscience take a chance on using that, either.

The next step is to visit my health practitioner as I continue to wait for my thyroid to go back to normal. If the symptoms become too bothersome to wait the 9 to 12 months’ time that this could take, I will ask her advice about taking Armour thyroid.

Even though I am a strong advocate of natural medicine and holistic therapies, I have to caution anyone who is thinking about self-prescribing any kind of thyroid NOT to do that without the advice and counsel of a licensed medical practitioner! There is just too much margin for error and a very strong possibility you might ruin your health. These are strong hormones and definitely nothing to take without medical supervision.


Never self-prescribe! Always be under the care of a licensed health practitioner to administer thyroid 
medication or supplements, and to measure thyroid hormone levels.


How Long Will the Symptoms Last?

I have read that it takes up to a year for thyroid disorder symptoms of hypothyroidism to correct after a CT scan. Even though I feel I had a valid reason to get the scan (family history of aneurysm is one reason), I don’t think I personally will be having a contrast study again, because of these side effects. However, each person must make his or her own decision, and I think this article may be helpful for you to see how CT scans with contrast might affect your thyroid health and to ask your doctor for advice if you are concerned.

Not everyone’s situation will be the same as mine; please work with your health care provider to advise about the risks of a CT scan and the reason you are having the scan done. A CT scan can be done with contrast or without contrast, but with contrast, a doctor can see more detail on the images. That being said, if you have ever had an allergic reaction to iodine or a bad  reaction to contrast dye, please inform your provider so he or she can request to have the scan done without the contrast.

A CT scan is a wonderful invention that can detect abnormalities in the body that are not visible with traditional x-ray studies; even so, ALWAYS be informed about any studies or therapies a doctor recommends for you.

Please Read!!

If you have ever had an allergic reaction to iodine or a bad 
reaction to contrast dye, be sure to inform your 
provider ahead of time. He or she can then help you decide 
the best test for your condition.


Always Be Your Own Advocate

Remember, it always pays to be your own health advocate: always ask questions if you have any doubts about treatment you are receiving and if you don’t understand the answers or don’t get cooperation from your health provider, ask again or change doctors. You don’t have to agree with any doctor, nurse, or other medical professional who blames your symptoms solely on (1) your age, (2) your gender, or (3) your weight, or tries to tell you “it’s all in your head.” To me, this means they don’t want to dig any deeper or admit they don’t have the answer. A good health provider will always see you as an individual rather than a statistic,and be willing to listen to your concerns instead of sloughing them off.

It’s understandable that many traditional doctors don’t know more about nutritional or holistic therapy, because they usually haven’t received more than a few hours’ training in medical school about nutrition and probably little or no training about alternative therapies. That is beginning to change, and now most doctors won’t put you down if you are helped by acupuncture or chiropractic, or vitamin therapy. If you have access to a holistic health practitioner or naturopath, you are very fortunate because you can then receive a full spectrum of care.

Whoever provides your health care, I’ve learned it is always a good idea to do your own research first before accepting anything that someone else tells you as the whole truth. (That includes this article, since it is based on my personal experience alone.) Do your homework!

More Thyroid Help


 Beat Hypothyroidism Naturally: Proven 3-Step Guide to Healthy Thyroid FunctionCheck Price Pure Encapsulations – Thyroid Support Complex 120cCheck Price

Update on My Thyroid Condition

What I’ve Learned

Looking back, I can now understand that my lab tests viewed over the long term show: hyperthyroid right after the CT scan, then a sudden change to HYPO-thyroid. In other words, my thyroid is not producing enough thyroid hormone. The good news for me is that my TSH lab values are now one-third of what they were, although the free T4 is only marginally improved.

In order to aid in the production of thyroid hormone, I have reintroduced iodized salt and seafood back into my diet. Also, after being cautioned about the dangers of distilled water for drinking, I asked my doctor about using a reverse osmosis water filter. She said that there is no good way to filter out fluoride from water without also filtering out essential minerals like calcium. She advised me either to continue using filtered tap water (I use a Brita filter), purchase a carbon block filter system, or add mineral supplements (if I were to continue to drink distilled or reverse osmosis filtered water). For now, I’m sticking with my Brita filter until I find a better system.

Also, since my thyroid values are improving, my doctor did not feel I needed to take thyroid hormone (Armour thyroid) right now. She provided me with a thyroid support supplement to take in the morning.

In addition, because I have a family history of thyroid disease (my mother was diagnosed with Graves’ disease), my doctor suggested that I request a full thyroid lab panel from my primary physician. This consists of: TPO (thyroid peroxidase antibody screen), thyroglobulin antibody, and TSI (Graves specific thyroid stimulating immunoglobulin) to see if I am predisposed to thyroid problems. She said that not everyone will have the same reaction to iodine contrast with a CT scan, so a hereditary tendency might be the reason.

which foods are good for your thyroid
Photo by author


Which Foods are Good for Your Thyroid?

There are some foods which can lead to goiter (an abnormal enlargement of the thyroid), and which are referred to as “goitrogenic” foods.

which foods are good for my thyroid
Photo, Gadini @Pixabay

Although she stated that you’d have to eat these foods for breakfast, lunch, and dinner to cause a problem, my doctor did say that there are some foods that can promote goiter: those foods include soy, raw kale, cabbage, and broccoli. Again, you’d have to eat a LOT of these foods, but it’s something to keep in mind when you have thyroid issues.

Foods that help support the thyroid are: Brazil nuts (they contain selenium), sea vegetables like kombu and wakami (contain iodine), chicken and fish (contain protein),and oysters. Kale, cabbage, spinach, and broccoli are good, as long as they are cooked and not raw. Iodized salt is also beneficial in small amounts. I’ve been drinking coconut water for hydration and for the added minerals.

In general, it’s always smart to use good judgment about what you eat and don’t go overboard eating too much of any one thing. Maintain good health habits of getting out for fresh air and exercise, staying well-hydrated, and avoiding sugary and fatty foods. Stress can be a factor in many cases, too.

I hope this post has been helpful to those who are going through similar issues.

Important Note

Please do not consider any of this as medical or health advice: 
I caution that this is my experience only; your situation may be
different. Always consult your health practitioner for this 
and any other health concerns.