Vitamin D replacement dose: Referring back to a... - Thyroid UK

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Vitamin D replacement dose


Referring back to a previous post - my GP has given me 20,000 iu daily for 15 days of vit D3 then after that I am to take 1 per week.

I suggested a reduction of Levothyroxine to 175 one day and 150 next and he said that sounded like a good plan.

I haven’t got the figures yet but he told me the thyroid antibodies were done but were not raised.

The vit D seems to be much higher than the nhs recommendation SlowDragon sent a link to but the pharmacist didn’t comment so it must be ok.

I will have my bloods redone in 3 months.

4 Replies


Each Health Authority will have their own guidelines. What your GP has done is actually given you the loading doses which is normally given for levels below 30nmol/L, and they total 300,000iu over a number of weeks. What I would do if I were you is take what has been prescribed but ensure you retest after 3 months. You need to reach what's recommended by the Vit D Council, the Vit D Society and Grassroots Health which is a level of 100-150nmol/L. Once you've reached that level then you'll need a maintenance dose which may be 2000iu daily, maybe more or less, maybe less in summer than winter, it's trial and error so it's recommended to retest once or twice a year to keep within the recommended range. You can do this with a private fingerprick blood spot test with City Assays

Your doctor wont know, because they are not taught nutrition, but there are important cofactors needed when taking D3 as recommended by the Vit D Council -

D3 aids absorption of calcium from food and K2-MK7 directs the calcium to bones and teeth where it is needed and away from arteries and soft tissues where it can be deposited and cause problems such as hardening of the arteries, kidney stones, etc.

D3 and K2 are fat soluble so should be taken with the fattiest meal of the day, D3 four hours away from thyroid meds.

Magnesium helps D3 to work. We need Magnesium so that the body utilises D3, it's required to convert Vit D into it's active form. So it's important we ensure we take magnesium when supplementing with D3.

Magnesium comes in different forms, check to see which would suit you best and as it's calming it's best taken in the evening, four hours away from thyroid meds

Check out the other cofactors too.

Thank you. That is very helpful. Can you recommend the dose of Vit K and magnesium.? The links from my previous post suggested bath salts for magnesium absorption and leafy green veg for Vit K. Would that be enough ?

in reply to annegal


It's recommended to take 90-100mcg Vit K2-MK7 for up to 10,000iu D3. You can get some from food but I don't know how much of what you would need to eat to get the right amount. A good K2-MK7 supplement is

There are many ways to take magnesium, epsom salt baths, magnesium oil, etc, also magnesium supplements. If considering a supplement you would need to decide which one suits your needs. For example, magnesium citrate helps with constipation. I gave you a link to an article which explained the different types of magnesium and what they were good for.

Thank you. That is most helpful.

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