Thyroid UK

Hypo and understanding affects of vitamin and mineral deficiency

Hi, I'm hypo and on 100mg levo and 3 x 20 mg lio a day.

I have read that being low / deficient in folate, ferritin, vit D, vit B12 and/or iron affects absorption of thyroid meds. As I'm on levo, I believe that I should be in the top quarter of the range for these.

My iron was not tested - GP told me it was the same as ferritin!!!!

I have very low ferritin 29.9 ( 10 - 204 ), low B12 617 ( 187 - 883 ). What affect will this have on my thyroid test results? I don't understand what it means by "isn't absorbed properly". I understand that I will not be getting the full benefit of levo and lio but does this affect the T4, T3, FT4, FT3 or TSH level blood tests?

Also, I was diagnosed vit D deficient three years ago and prescribed 2 x 400 iu tabs a day. I find that is not sufficient when there is little or no sun - my problem is that I can't store vit. D. I take more depending on the weather.

When I was diagnosed my result was 10 in a range of 12 to something. My latest test result is different. It was 84 in a range of over 75. I was told that makes it normal.

As a hypo sufferer is 84 sufficient or should I be taking more vit D?

I'd be really grateful for any help any one can give me.

Thanks in advance.

6 Replies

I was once biotin deficient and it wasn't picked up when I had my annual blood test so I don't think that is strictly true. I had Angular cheilitis and my doc was treating me with steroid cream as he didn't know I was deficient. I only found out when a dentist wouldn't treat me because of the leasions so I went home and Googled... I wrote a list of possibilities and went back to my doc and forced him to run more tests. He put me on a course of iron and B vitamins and the problem cleared up. My thyroid results were always normal during this time.


Ferritin and iron are not the same thing, but I can see why a doctor might say so. Ferritin is a molecule which holds the body's stores of iron and releases those stores as and when the body needs the iron. In fact one ferritin molecule holds up to 4500 atoms of iron.

Source :

There are circumstances when the body will keep serum iron itself quite low, and will shuttle any ingested iron into ferritin. Someone with infections or inflammation might have low in range serum iron and high in range (or over the range) ferritin. If the infection or inflammation is healed the body starts to release the iron stored in the ferritin and the serum iron will rise.

There are lots of other circumstances where the ferritin level is not a good indicator of iron levels. See the table at the bottom of this page :

When I was young the preferred measurement for deciding whether someone was anaemic was looking at haemoglobin levels. Now they use ferritin. In my opinion neither is sufficient on its own, but then I'm not a doctor.

Being low in iron (or less than optimal) makes conversion of T4 to T3 difficult for the body. Since T3 is the active hormone that makes people feel well, poor conversion has a big effect on well-being.

Referring to your vitamin D deficiency, you might die of old age before 2 x 400 iU of vitamin D per day will optimise your levels. You would need to find out what your level actually is, then ask for advice on the forum as to how much you need to supplement. Most people feel at their best with a vitamin D level around 100 nmol/L or even a little bit higher.

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Hi, Thanks for that. It looks like my vit D is a little low at 84 then. Unfortunately, I can only speak to a results line at my surgery and the person there is not medically qualified so can only read off the results as given by the lab.

I think, I may try again to get my iron tested.


84 isn't bad, so you obviously absorb your vit D supplements well. Perhaps you could increase your dose of vit D supplements just at the weekend, or three times a week perhaps?

I would be surprised if you got your doctor to give you a full iron panel, although its always worth a try. I've had all sorts of problems with low iron over the years, and yet I've never had one done by my doctor. I had to pay to get the full works done.


Dizzy964, FT4 in, or near, the top quadrant of range is optimal for people on Levothyroxine (T4) only. You are also taking 60mcg Liothyronine (T3) so it is likely your FT4 is much lower, possibly below range, as high levels of T4 aren't needed for conversion to T3 because you are taking T3 direct.

Ferritin is stored iron. Ferritin below range may indicate iron anaemia. Ferritin is optimal half way through range so supplement iron and take each tablet with 500mg-1,000mg vitamin C to aid absorption and minimise constipation. Retest in 6 months. Iron and vitD should be taken 4 hours away from Levothyroxine.

VitD 84 is in the 75-200 is the optimal replete range. Most people are comfortable with vitD around 100. If you feel well continue with your current dose or increase it slightly.

B12 617 isn't low, it's <500 which may cause neuropathy. PAS say 1,000 is optimal so you could supplement 500mg-1,000 methylcobalamin sublingual lozenges, spray or patches and take a B Complex supplement to keep the other B vits balanced.



Thanks for that.

I don't feel well and haven't felt well since last October. The problems been that two doctors at my surgery have decided that it is all due to being over medicated on T3 and won't consider any other possibilities. The second gp even admitted that she knew nothing about the thyroid or it's problems. She just insisted I reduce lio and she immediately reduced my prescription well below what we had agreed I would reduce to. The surgery has ignored my request to put it back up to the level we agreed let alone the level I was previously on.

I put myself back up to my previous dose when I started having chest pains, and difficulty breathing - it scared me as I'd not had this before. It stopped three days after returning to my previous dose. I read on line this was a symptom of being under medicated.

I'm seeing a consultant on the 4th at Hull. I wanted to know before hand what to tell him. I'm afraid I don't have any faith in doctors ( or consultants ). I've had too many wrong diagnoses over the past 18 years, when all the signs were there. I've had too much unnecessary suffering because of it. I now like to know the facts before I see consultants. I think it gives them a better chance of getting things right.


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