Hypothyroid + Vitamin D/ amount to Take when Deficient

Hi, I've recently been tested for a whole bunch of Vitamins thanks to folks advice on this great forum . . . and not my GP i'm afraid to say. My T4 is 8.8 and T3 is 4 and Vit D's 34.7 . . so low

So T4's low and T3's normal . . . so how, being on NDT do I increase T4 without also increasing T3 is one question please? Also, I've been prescribed Colecalciferol 800iu one a day, however on a couple of sites I've looked at people advocate much larger doses i.e 5000 iu plus!?

Any help would be appreciated . . . thank you for looking.

19 Replies

  • Hi

    I had Vitamin D deficiency middle of last year, it totally messed up my thyroide hormone uptake and made me very ill.

    My Vitamin D level was 17 (range 50-200) and was given 10,000IU/day D3 for a month to build it back up. 1000IU thereafter for life. Made a big difference very quickly too :)

    Hope this helps :)

  • thank you for your reply. I wasn't aware that low D3 could mess up thyroid hormone take up but I certainly haven't felt well for . . . . seems forever . . . so fingers crossed you are right and I too will feel better with D3 supplement.


  • Critical for absorption of thyroid hormone, so I found out :o My endocrinologist also agrees :) Plenty of posts on this forum to confirm this.


    "Most important for those of us who are hypothyroid, the symptoms of low vitamin D can look like low thyroid, such as fatigue and general aches and pains. Since vitamin D is critical for bone health, adequate levels may be necessary to prevent bone problems often associated with poor thyroid hormone replacement with T4-only. Plus, vitamin D levels (along with levels of iron and cortisol) need to be optimal for thyroid receptors to respond properly and for thyroid medications work properly"



  • Dashi2208,

    It'll take a long long time for 800iu to make any difference. I would supplement 10,000iu D3 for 6-8 weeks then reduce to 5,000iu daily and retest in June/July.

    FT4 is often low when taking NDT or T4+T3. Most people taking NDT feel they are optimally medicated when FT3 is in the top third of range.

  • thanks Clutter. I think the Dr. errs on the side of caution . . . 'do no harm' and all that but I'm impatient to feel well again and will follow your suggestion.


  • Hi, . . . my thoughts exactly

  • Unless you are on other medication which is known to interact with vitamin D, the GP will be prescribing based on local NHS trust guidelines. (You can actually Google them for a lot of areas.)

    Unfortunately some trust guidelines are based on old research, and also seem, in my opinion, to be based on budget requirements rather than patient need.

    800IU tablets are very cheap for the NHS to buy there as higher supplement levels can get very expensive. So I actually know people whose GPs have prescribed something like 6 x 800IU tablets to take daily rather than prescribe them 5,000IU tablets. In my area rather than do this to save money they tell you to buy your own supplements if your level of vitamin D3 is over 25nmol/L as they expect you to take a supplement daily for life.

  • Hi Clutter, my usual regime is to take 1.5 grains at around 6a.m. I awoke at 4 this morning abruptly, feeling agitated. I took an extra 1/4 of a 1.5 grain pill ( probably less maybe even 1/8 ) and felt immediately calmer and fell back to sleep. So I'm thinking that 1.5 grain isn't enough to sustain a 24hr period. with free T3 at 4 I guess that I'm in top third of range. I'm thinking however that I might increase my dose slightly by either 1/4 or 1/2 a grain. Is it better in your opinion to try 1/2 , possibly overshoot and par back or should I be more cautious and try 1/4? Both difficult with a 1.5 pill to split I've just realised!


  • Dashi2208,

    No point in guessing what the range is, they can vary from lab to lab. FT3 4 is low in many UK labs.

    It's better to try 1/4 grain than to over shoot with 1/2 grain but I think the best you'll be able to do is to quarter a 1.5 grain pill unless you buy 1 grain tablets.

  • Hi Clutter,

    when you say low what do you mean please ? I can interpret that to mean it's near to 2.63 and close to bottom of range, so good . . or low as in not enough T3 so not so good . . . . .!?

  • oh, I think I see what you mean. Slightly confused 'cos I assumed the range would be universal. My lab states the range to be 2.63 to 5.7 . . ...so that puts my result in the middle more or less

  • Dashi2208,

    FT3 4 is less than 1/2 way through range. I would increase dose and aim for FT3 4.65-5.7.

  • ok . . .will do. thx

  • also, I'll let you know, guinea pig-wise, how it goes if you like

  • Ive also had low Vit D results 18 & was prescribed the same as you however after joining a facebook page called Vitamin D wellness I got loads of info on the best type & dose of vit D to take, (gel caps) when to take it & how ! ive settled on 2000 iu per day & some K2 & Magnesium feel ok so far .... I DID however check with my g.p who okayed it all !

  • D3 say 10,000 IU plus K2 daily. Blood test for D after 6 weeks.

  • Some years ago now, I was found to be low in d,, about same level as yours. Doc told me nhs guidelines if deficient is 20,000 units a week for 12'weeks then it's a case of finding a decent maintenance dose. What you've been given is that standard maintenance dose without having had the loading dose. Levels need to be 75 nmols and above. I took my initial loading dose which built things up nicely but once I tried the small maintenance dose it dropped quickly. We're all different , I still need min 10,000 a week. Bit more during winter. By way, those 800 unit ones the doc gave me had peanut oil in, yuk. Bad quality. I take healthy origins ones as advised on here, wife takes drs best.

    Obviously, I'm not telling you what to do or what you'll need, this is merely what happened to me and what I need.

  • Hi, thanks for your reply. It's so nice to have a little contact with folk who are in the same boat and not be at the total mercy of the opinion of a fallible, if well meaning, medical establishment.

    I looked at Healthy Options and there seems to be quite a choice of supplier out there. Mind if I ask where you got yours? By the way you may need to private message me if you do answer or you'll get told off.


  • Hi,, yes I know what you mean, this forum has been such a help to me over the time. I do believe we're ok to suggest vitamin suppliers but thyroid UK website has some suggestions on there. I get mine from Amazon.

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