What dose vitamin D and do I need to take vitam... - Thyroid UK

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What dose vitamin D and do I need to take vitamin K2?


Results of my blood test show I am deficient in vitamin D.

Results - D3 = 15.6 nmol/L, D2 = 2.8 nmol/L, Total vitamin D 18.4 nmol/L. Results show 15-30 as deficient.

Do I need to take a supplement with both D2 and D3 or just D3 and do I need to take vitamin K2 alongside it, or get a supplement that contains both?

I've read on the Vitamin D council website they recommend 5,000 I/U daily.

7 Replies


Total vitamin D 18.4 nmol/

Your GP should provide loading doses for this level.

NICE treatment summary for Vit D deficiency: cks.nice.org.uk/vitamin-d-d...

"Treat for Vitamin D deficiency if serum 25-hydroxyvitamin D (25[OH]D) levels are less than 30 nmol/L.

For the treatment of vitamin D deficiency, the recommended treatment is based on fixed loading doses of vitamin D (up to a total of about 300,000 international units [IU] given either as weekly or daily split doses, followed by lifelong maintenace treatment of about 800 IU a day. Higher doses of up to 2000IU a day, occasionally up to 4000 IU a day, may be used for certain groups of people, for example those with malabsorption disorders. Several treatment regims are available, including 50,000 IU once a week for 6 weeks (300,000 IU in total), 20,000 IU twice a week for 7 weeks (280,000 IU in total), or 4000 IU daily for 10 weeks (280,000 IU in total)."

You could go it alone and follow the guidance above. If you do this my suggestion would be to take 5,000iu D3 daily for 8 - 9 weeks then retest. No need to take D2, D3 is fine unless you are vegan.

Retesting is important because you need to know the dose you should take based on your new level.

The Vit D Council recommends a level of 125nmol/L and the Vit D Society recommends a level of 100-150nmol/L. Once you reach this level then you'll need a maintenance dose to keep it there, 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 an NHS lab which offers this test to the general public:


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 if taking tablets/capsules/softgels, no necessity if using an oral spray.

If you take warfarin or any other blood thinning medication, you will have to do some research. K1 is the blood clotting form of Vit K, K2 is different, but you should satisfy yourself.

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 if taking tablets/capsules, no necessity if using topical forms of magnesium.


Check out the other cofactors too (some of which can be obtained from food).

AnneEvo in reply to SeasideSusie

Thanks for the information Susie. I'm thinking of supplementing myself in the first instance as the nurse practitioner wants to see me in 3 months as she put me on iron tablets to see if it combats tiredness. She inidicated she'd be willing to test vitamin D when I go back but of course I don't want to wait till then. I was using a magnesium spray but it itches my skin. I'll try a different form. I'll check out the links you've provided.

AnneEvo in reply to SeasideSusie

Having read the NICE guidelines I'm wondering about going to the doctor's. I suppose I was reluctant to go and say I'd had a test done myself. :-/

SeasideSusieAdministrator in reply to AnneEvo

It's up to you but I didn't bother with my GP when my Vit D was 15nmol/L. I sorted it myself and in 2.5 months my level was nearly 200. You will be able to source a much better Vit D supplement yourself, but have a think about it and decide what you'd prefer to do. You'll have to buy the cofactors yourself, doctors don't know anything about those.

AnneEvo in reply to SeasideSusie

Thanks again Susie.

Hi when I first had my Vitamin D tested three years ago it was very low, like yourself. I joined this site and took Seaside Susie's advice. I don't bother going to the GP I just order mine online. In the winter I take softgels 5000IU everyday I also take K2 softgels. These two work together take with the fattest meal of the day. You can then order your own test after a few months.

Here’s a good combo .... Vitamin K2, D3 and Magnesium Combo: 3-in-1 Formula by NutriZing. 3000IU Vitamin D3, 150mcg VIT K2 (MK-7) and 20mg Magnesium in a Single Capsule. Maintenance of Normal Bones, Teeth & Muscle Function.: Amazon.co.uk: Health & Personal Care

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