Thyroid Disorders Community
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Avatar universal

Levothyroxine and iodine supplements

Hi. My question is, am I likely to have caused myself permanent damage by stupidly taking iodine supplements as well as levothyroxine for six weeks?

I was diagnosed with an underactive thyroid about six weeks ago and put on 25mcg levothyroxine daily. At the time, I suspected that the vegan diet I had been following for nearly a decade had probably caused the thyroid problem, as vegan diets can be notoriously low in iodine. I asked my GP if this was possible and whether taking iodine supplements might help. She said she thought it very unlikely that anyone in the Western world would be iodine deficient, but that supplements were unlikely to do me any harm, either, so I could try them if I wanted.

I started taking a multivitamin which included 150 mcg iodine daily and also started eating a bit of dairy again, because I was so frightened that my low-iodine diet had damaged my thyroid. For a few days, I also took a 300mg kelp supplement (although I skipped the multivitamin on those days).

From looking on the internet, I now realise that this was absolutely the wrong thing to do (especially the kelp) and that you should never mix levothyroxine and iodine supplementation. I've now stopped both the multivitamin and the kelp, but I'm really, really worried that the sudden massive intake of iodine for six weeks will have totally murdered my thyroid. I'm reluctant to discuss this with my GP (although I will bring it up at my next review in 6 weeks' time), because it seems clear to me from her earlier advice that she doesn't really understand the impact of diet and/or supplements on thyroid function.
21 Responses
Avatar universal
I really wouldn't be too worried.  I read the link, and I think what he refers to is what I said above...iodine can exacerbate the autoimmune response with Hashi's (he doesn't say that in so many words, but I think that's the message).  On the other hand, iodine might skew thyroid TESTS.  

Iodine is necessary for the production of thyroid hormones.  So, were you deficient, iodine could help.  Though iodine deficiency is rare in the U.S., it is possible.  Do you use iodized salt?

Also, you're on a very low dose of levo. I really highly doubt you've done your thyroid any damage.  As with anything else, just go easy on any supplements...stay within RDA.  
Avatar universal
Iodine supplementation can be contraindicated if you have Hashi's as it can exacerbate the autoimmune response (whether or not you anre on levo).

"...you should never mix levothyroxine and iodine supplementation."  I don't know what you've been reading, but this is not true.  Do you have a link?  
Avatar universal
I found quite a few web forums where people were saying this and other pages like this one http://thyca.org/levothyroxine.htm

I know these are hardly authoritative sources and I'll be relieved if it's not true!

I certainly don't think I've done myself any good - I had bad side effects (a few episodes of palpitations and a burning feeling in my gullet) a couple of weeks after I started taking the levothyroxine, which I put down to the drug, but which I now think are more likely to have been caused by the kelp, as they cleared up once I stopped it.
Avatar universal
Thanks so much for replying - you've made me feel a lot less anxious.

I'm in the UK, where it's less routine for salt, bread etc to be iodised than in the US. But I think it was probably a mistake to try to eat more iodine-rich foods AND use supplements - I now realise one or the other would have been sufficient and I'm going to lay off the supplements from now on. I think I just went into panic mode when I got the diagnosis.

Avatar universal
I've been on Levothyroxine for 2 years now. When I started taking it I lost 15 lbs right away, yay! I started taking iodine and 25mcg Synthroid for 2 months now. It's been a disaster! I've had dizzy spells, heart palpatations daily, shortness of breath and have gained 13lbs in 2 months!
Bad idea.
I'm going to stop taking the iodine supplement.
Iodine deficiency is very high in the U.S. and iodized salt is not enough to help. I've heard that it's good to stay away from iodine-rich foods ie. strawberries, kale, spinach while on Levo or Synthroid.
Good luck!
Avatar universal
I think the foods you refer to...strawberries, kale and spinach (among many others)...are not iodine rich, but goitrogens, which are foods that can cause thyroid inflammation.  The goitrogens in these foods are killed by cooking, so they're only an issue when eaten raw.

I'm curious as to whether you adjusted your Synthroid dose when you added the iodine supplement.  I also wonder if your 25 mcg of Synthroid is sufficient to bring your FT3 and FT4 levels up to target levels (not just in the bottom of the range).  Weight gain is a symptom of hypo.  

Please post recent thyroid labs if you have them and include refeence range that vary lab to lab.

Do you have Hashi's?  
Avatar universal
I was kept on 25 mcg levothyroxine for a long time. I am familiar with the dizzy spells, light-headed days, exhaustion, headaches, body pains, out of it feelings, brain fog, joint pain, etc.  My doctor was basing keeping me on such a low dose from just a TSH test.  Once my TSH got around 1 she was happy ~ and I was miserable.

I wised up and found a new doctor.  She noted that my light headed days and dizzy spells was from my heart which was at 50 bpm in office.  She tested my Free Ts and found them extremely low.  Since February I have raised my levels considerably with a higher dose of NDT, but am still working towards getting my Free T4 to mid range and Free T3 to upper range. My TSH now is .008.   Huge difference! I feel wonderful....
Avatar universal
I'm on Armour, strawberries kale spinach, are these a no on Armour too? but if there cooked its ok?
Avatar universal
Strawberries, kale and spinach (among many others...google goitrogens) are goitrogens.  Goitrogens are substances in food that can cause thyroid inflammation.  They can make your thyroid swell causing discomfort.  They do not interfere with any thyroid meds; they can interfere with your thyroid function (if you have any left).

Yes, cooking does destroy goitrogens.

I eat goitrogens all the time, raw and cooked.  They don't bother me at all (I think my thyroid is dead and gone).  As with everthing else dietary, if avoiding them makes you feel better, then do so,  If not, there's no reason not to eat this group of foods which contains some very healthy items.  Broccoli, cabbage and all the cruciferous veggies contain goitrogens as well as the others already mentioned.
Avatar universal
I was just recently diagnosed with hypo  tsh level was 8.91  my pcp started me on 25 mcg levothyroxine, level dropped to 6.85 so levo was increased to 50 mcg,  I also purchased iodine plus 2 on internet taking( 12.5mgwith 15mcg of selenium and 15mg b2) one pill daily,  Am I doing a bad thing, feeling much better than before.
649848 tn?1534637300
If you have Hashimoto's, iodine is contra-indicated, as it can make the auto-immune reaction much worse.  Additionally, iodine can make hypothyroidism worse, if you take too much of it... it should always be taken under doctor's supervision.

Vitamin B-12 and selenium are fine to take; but you should get tested for B-12 to get a baseline result, as many people who are hypo are found to be deficient.
Avatar universal
I would like to come off the Levothyrox ine as I'm having too many side effects! Is it possible to take kelp tabs and iodised salt instead? If I'm very tired (which I seem to be  out of the time) I take a kelp tablet and a great weight seems to be lifted off me and I feel "human again".
649848 tn?1534637300
It sounds like, perhaps your levo dosage needs to be adjusted. The side effects of Levothyroxine are, typically, those of either under or over medication.  If you'll post your current thyroid hormone labs, with the reference ranges, we'll be happy to take a look at them and give you our opinion.

As noted above, iodine is, typically, contra-indicated if the cause of your hypothyroidism is Hashimoto's as it can make the autoimmune response greater.
Avatar universal
I recommend you read Dr. David Brownstein's books on Thyroid and Iodine.  I learned personally that iodine can exacerbate Hashimoto's, but it's deficiency could also be the underlying cause.  I'm at 50% of what I should be on Iodine.  I am working on this myself right now, and it's challenging, but not necessarily wrong.  Best of Luck.
649848 tn?1534637300
Blackbroom hasn't been active on the forum since she posted this thread in 2013, so it's unlikely she will respond to your comments.

While too little iodine can be the underlying cause of hypothyroidism, along with exacerbating Hashimoto's, too much can also  hypothyroidism.

Hashimoto's is the number 1 cause of hypothyroidism in the developed world.
15079583 tn?1438292130
TSH:   2.22    range: 0.35 - 4.94
T3 Free:  2.8   range: 2.3 - 4.2
T4 Free:  1.4   range: 0.7 - 1.5
Tpo (4 years ago) was 390  range: <35

I was on .112 mcg levothyroxine at time of test which was last week and did not know until recently to not take the pill within 24 hours of test - is that correct?   just found out about that Tpo test 2 days ago, and was told i didn't need to retest... is that correct?  

my endo thinks that because my results are within limits that my insomnia, exhaustion, depression, constipation, etc., do not have anything to do with my thyroid.  my pcp thinks that iron, b-12, vit d, rbc magnesium are unnecessary tests.  (i fired her today, btw.  :)  (something feels right with the world in all of this!)

i recently went looking online for relief and found a product that is highly recommended by users, even those who take levo, and it does contain 225 mcg of potassium iodide.  it also has selenium, folic acid, zinc, b-6, b-12 and copper; ashwagandha, guggul gum and tyrosine.  

should i really not take this??  with all the good (supposed) stuff in there, will the iodine hurt me, or be p*ssed away?  i've been so confused about iodine for 17 years and i'm tired of being tired.  tired of the docs passing me off to each other, especially with regard to blood work.  

p.s.  i am looking for a functional med doc and will be ready when i have the $$ to do so.  i am a military vet and mad as hell that i can have all the pills i want, but not a decent answer about diet, blood work and supplements to take.  

any help is appreciated.

649848 tn?1534637300
It's not necessary to refrain from taking your levothyroxine for 24 hrs prior to doing thyroid blood work.  It's really best not to take it until after your blood draw, but because of the long half life of levothyroxine, and the time it takes to fully enter your blood stream, it's probably not going to affect your results terribly much.  

Iodide is a form of iodine, which is not recommended when one has Hashimoto's as it can make the autoimmune reaction worse.  Potassium iodide is a man-made salt compound of iodine.  It not only increases your iodine content, it increases your potassium levels, which can be dangerous if you don't need additional potassium.  It can also increase your sodium levels.

Looking at your blood test results, it looks more like your problem is that even though, both FT4 and FT3 are "in range", your FT4 is too high in its range and your FT3 is too low in the range.  Your FT4 is at 88% of its range, which is considerably higher than the recommended mid range (50%) and your FT3 is much lower than the recommended upper half to upper third of its range.  FT3 should be higher in its range, as a percentage, than FT4 in its range.

It appears that you aren't adequately converting the FT4 storage hormone to the usable FT3.

Are you getting your medical care through the VA?  We've sometimes known vets to have a hard time getting adequate thyroid care through the VA...

You really should try to get vitamins D, B-12 and ferritin tested.  Vitamin D and iron are necessary for proper metabolism of thyroid hormones.  

The selenium has been shown to help with conversion of FT4 to FT3.
15552658 tn?1441320068
"My doctor was basing keeping me on such a low dose from just a TSH test.  Once my TSH got around 1 she was happy ~ and I was miserable."
As long as your doctor's happy, that's all that matters. *close sarcasm*
Avatar universal
you should never take vitamin supplements.
I have been diagnosed with graves 1998 in Germany.
As a supplement, i use Moringa leaves 1 teaspoon in the morning and evening and it works great for me, got them in my own garden ( lucky me)
Try to avoid Iodine in anyway you can to prevent flareups .

649848 tn?1534637300
I'm not sure why you say one should never take vitamin supplements... If a person needs them, it's perfectly okay to take them... many of us are deficient in quite a few vitamin/minerals since we have absorption issues and we have no choice but to take supplements.
Avatar universal
Use BLADDERWRACK instead of KELP, it will be much healthier for you.
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