Can iodine affect thyroid medication test resul... - Thyroid UK

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Can iodine affect thyroid medication test result numbers?

DizzyD profile image
16 Replies

Hi all few days ago I was prescribed a medication for atrial fibrillation, namely Amiodarone. It's contains iodine and if I had a thyroid which I don't my thyroid would have to be monitored regularly on this medication.So by having no thyroid I do not need to have regular thyroid checks.

But I was wondering if iodine can interfere with thyroid medication or test result numbers that I have done in the future.

Look forward to any replies from you knowledgeable people

Have a wonderful evening

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DizzyD profile image
DizzyD
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Jaydee1507 profile image
Jaydee1507Administrator

There is a pinned post here with a lot of information about iodine. healthunlocked.com/thyroidu...

Iodine is not recommended in hypothyroidism.

tattybogle profile image
tattybogle

funnily enough i was just reading this in connection with something else ,, it say's Amiodorone affects deiodinases ( so conversion of T4 to T3, and T3 to T2 , and T4 to reverse T3 could all be affected )

sciencedirect.com/science/a...

Matthew Kim, Paul Ladenson, in Goldman's Cecil Medicine (Twenty Fourth Edition), 2012

"THYROID.

Thyroid Hormone Transport and Metabolism

Circulating thyroid hormones are more than 99% bound to three classes of plasma proteins. Thyroxine-binding globulin (TBG) functions as the principal transport protein. Thyroxine-binding prealbumin and albumin make lesser contributions to T4 and T3 transport in blood. Pregnancy and exposure to pharmacologic doses of estrogens can increase TBG levels, as can hepatitis, familial TBG excess, and certain medications, including 5-fluorouracil, tamoxifen, and methadone. Conversely, decreased TBG levels may occur with systemic illness, severe hepatic disease, nephrotic syndrome, and treatment with androgens, glucocorticoids, and slow-release nicotinic acid. Whereas total T4 and T3 levels rise and fall with changes in TBG, free T4 and T3 levels remain constant. Familial dysalbuminemic hyperthyroxinemia is an autosomal dominant disorder characterized by the production of albumin that binds T4 with a high affinity. Affected individuals may present with high total T4 levels and normal free T4 levels. The receptor binding and biologic activity of T3 is eight-fold greater than that of T4.

More than 80% of the T3 present in target tissues is derived from T4 through the action of deiodinase enzymes that convert T4 to both T3, which contributes to the pool of T3 in the circulation, and biologically inactive reverse T3. The activity of deiodinase may be inhibited by systemic illness; iodide-containing compounds, including amiodarone and radiocontrast agents; glucocorticoid therapy; and selenium deficiency. Type 2 deiodinase is present in the pituitary gland and brain. Type 3 deiodinase is present in the glial cells of the central nervous system. It deactivates thyroid hormone by inner ring monodeiodination, a process that converts T4 to inactive reverse T3 (rT3) and T3 to inactive diiodothyronine (T2). Type 3 deiodinase is also expressed in placenta, accounting for the increased thyroxine dose requirement in pregnant women."

DizzyD profile image
DizzyD in reply totattybogle

Tattybogle that information is way about my pay grade. In layman's terms what does it all mean? Will I have faulty TSH results? Can I expect worse hypothyroid symptoms?

helvella profile image
helvellaAdministrator in reply toDizzyD

The TSH test should be an accurate measure of the TSH you have in your blood. But it might well not be the same as it would have been without taking amiodarone.

The amiodarone can affect the conversion of the thyroid hormones in your body. That is, for one example, the rate at which T4 converts to T3 or reverse T3. (Other examples include the conversion of rT3 and T3 into T2.) But the balance of the effects is not simple to predict.

Make sure you maintain awareness. If you think things are changing and you feel under- or over-dosed, request another test.

DizzyD profile image
DizzyD in reply tohelvella

Thanks helvella, lots of info to get my head around. Presently, I dose 75-50 levo alternate days. Also dose 30mg NDT daily. Thyroid numbers tested a few weeks ago were not that great. God only knows how Amiodarone will mess with my thyroid medication. I think it would be pointless requesting TFT via NHS...they do not test ft3. Is it possible to request deiodinase test via NHS? If it is I could request this test asap so that the results could be compared against any future dio tests..!

helvella profile image
helvellaAdministrator in reply toDizzyD

Deiodinase enzymes are not available as regular diagnostic tests. Everything like that is from research rather than treatment.

The important things are:

First, you know there might be an issue;

Second, you know that nothing is definite;

Third, that you have to remain aware and get TSH/FT4/FT3 tests if you feel changes.

That is three steps ahead of many! If you do feel wrong, don't convince yourself it is all in your head.

tattybogle profile image
tattybogle in reply totattybogle

it was a bit over mine too, which is why i put it in full ... lol.

.... it means that whoever told you "the need to keep an eye on thyroid blood tests doesn't apply to you, because you don't have a thyroid" , was wrong .

Amiodorone clearly does have the potential to affect thyroid hormone levels even in someone without a thyroid .

.... possibly to a lesser degree that someone who does have a thyroid ., but the potential for an effect is still there.

Iodine affects T4 and T3 PRODUCTION in the thyroid, so that part wont affect you. (the production part is what they were thinking of when they said it doesn't apply to you )

But the article is talking about CONVERSION, not production .

Some conversion of T4 to T3 happens inside the thyroid ,(so that part won't affect you either).

BUT , a lot of the conversion of T4 to T3 happens OUTSIDE the thyroid (in other organs of the body, eg liver etc) .. and that will still affect you , even with no thyroid.

Deiodinases are what do the conversion , there are three of them Dio1 , Dio2 , Dio3....

So if Dio2 is affected , your rate of conversion from T4 to T3 could be slower.. (you would make less T3 from the levo (T4) you take) .

if Dio3 is affected your rate of clearance of T3 to T2 could also be slower (meaning the T3 you do have, lasts longer)

and those are just two possible effects ... since there are 3 deiodinases all doing different things in a complex way, there is no way to predict what might actually happen in an individual ... but if Amiodarone can affect / inhibit deiodinase action , then it COULD change your T4, T3 levels .... and if it does that , then your TSH level could change in response to the altered T4/ T3 levels.

So it would be a good idea to monitor your symptoms and TSH/ fT4 / fT3 levels to look out for any changes...even with no thyroid.

DizzyD profile image
DizzyD in reply totattybogle

That's amazing Tattybogle thank you so much. Honestly, I feel like going back to the Dr who said that I don't need to be concerned about Amiodarone effecting me because I don't have a thyroid. Think he was a pharmacist on the hospital ward but no sure. He did say my thyroid numbers were great!!! Asked him if Ft3 was included in the results....nope they were not. Says a lot doesn't it?

Going to print off the invaluable replys you so kindly posted for future use to educate myself and present to any medical people who I see in the future...including endocrinologists.

When the pupil is ready the teacher will appear. Hey you my teacher now I can teacher Drs with information you sent me. Priceless Tattybogle really appreciate the help and support. You are amazing.

Brightness14 profile image
Brightness14

Lots of foods contain iodine especially seafood and fish which I eat a lot of with no thyroid.

Even eggs and bread too. You are taking a small amount of medication for someone with no thyroid, are you well on that dose?

kiefer profile image
kiefer

Are you supplementing with magnesium? This is what I did for my father, who was placed on both amiodarone and warfarin for atrial fibrillation (it was a disaster). I began to increase his magnesium intake and his atrial fibrillation ceased.

DizzyD profile image
DizzyD in reply tokiefer

Yes I take magnesium along with other supplements all of which benefit the heart. My AFib is really severe though not just basic palpitations prescribed Flecainide last week two days later AFib went ballistic...peak cardio activity for 3hours just sitting. DISASTER! Hence the Amiodarone...!

houston8 profile image
houston8

Be SURE to have daily checks in general if ur on amiodarone. i don’t mean only thyroid hormone related but breathing issues, short ness of breath , getting winded more etc. One of amiodarone’s side effects is pulmonary toxicity which caused my stepmom to pass in 4 months. Amiodarone can be an ok drug but just make sure ur being monitored!!

DizzyD profile image
DizzyD in reply tohouston8

In all fairness only been on them for 3 days. It's such a relief to be AFib free. My a fib was really severe...last attack was Friday gone. Fitbit revealed that I was in peak cardio activity for 3 hours while in bed. This happened after 4 doses of Flecainide taken over two days. So yes I am very wary of medication but I have no other option available to me. I do intend to get monitored even if I have to fight for it.

So sorry your stepmon passed away. Will look up pulmonary toxicity symptoms to educate myself.

houston8 profile image
houston8

see amiodarone “survivors and family members support group” facebook group for more info

DizzyD profile image
DizzyD in reply tohouston8

Will do...!Sincere thank you

houston8 profile image
houston8

awesome it’s working for you. If u need any other info on staying safely on it i will help. If i can help in any way to keep even one person safe i am happy .

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