Thyroid UK
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help reading blood results

hi I have just received my latest blood results today all seems ok. and it says no further action, but I,m a little confused with some of the results,

serum ferritin- Normal-No 32 ug/l 11.00-307.00 ugl

serum vit b12-(SJ17021 ) - No 166 ng/l 145.00-910.00 ng/l Action

does this mean I am deficient in B12 as I have been so tired for weeks or am I interpreting these figures wrong I would be greatful for your advise thanks

14 Replies

As far as your doctors are concerned you are within the lab range so they don't have to treat you so you need to treat yourself.

The recommendations on this forum for:

Vitamin B12 - take methylcobalamin lozenges either Jarrows or Solgar to get your level to around 1,000

Ferritin - one ferrous fumerate tablet twice per day with a vitamin C supplement and water. Take 4 hours away from thyroid meds and 2 hours away from other food, drink and supplements to prevent interactions. The vitamin C is to aid absorption and decrease constipation. Get a pack of 84 ferrous fumerate and 7 days after you have finished the iron tablets get a ferritin blood test to check what your levels are and if there are any issues. The test will have to be done privately. You want your ferritin to be around 80 minimum and up to halfway in the range.

All supplements can be purchased from Amazon.

As you should be self-aware in why you need to do this ensure you read following links:

Ferritin -

Vitamin B12 -

This is because no one on this forum is legally responsible for your health so you need to ensure that you have an understanding of why you are doing what you are doing.


Although your results are within the reference ranges, the reference ranges are too low for most people so I would agree that this could be the reason for your tiredness.

Most people do best when their B12 is above 500. I'm not entirely sure of the best level for ferritin but it is significantly higher than yours is currently reading. You may benefit from iron supplements too. Often taking B12 causes a temporary drop in iron levels anyway so it might be a good idea to get an iron supplement too provided you don't have a health problem that means you can't take iron.

Remember to not take iron at the same time as thyroid hormones.

I hope that helps

Pink x

1 like

thank you so much for the info, I will get some methylcobalamin and give it try and see if I feel any better, the only problem is I cant take vit C as it gives me awful tummy ache I have graves and take carbimazole would iron or b12 interact with meds, another thing I forgot to mention ! I have been losing my fingernails for months now some grow back again but eventually they come away from the nail bed GP did a fungus test and it was ok he shrugged his shoulders and said he had no idea Soooo where do I go from there could this be due to B12 def.


I'm not sure about vitamin C. There may be an alternative form that is gentler. bluebug might know.

It might be worth posting a separate post about the fingernail problem. Someone on here might have come across it before. My friend has this problem and the doctor can't find the cause. It started when she was pregnant but it hasn't resolve since. I'd be interested to know what is causing it too so if you do find the answer please let us know! Meanwhile it might be worth looking to see if it could be a B12 symptom.


If you have only ever taken vitamin C in the form of ascorbic acid there are other forms of vitamin C that are easier to tolerate that might work for you.

You might cope better with it in the form of a mineral ascorbate. The commonest ones around are sodium ascorbate and calcium ascorbate.

But since most of us don't need additional sodium or calcium with our vitamin C I would suggest trying to find magnesium ascorbate. Many people are deficient in magnesium, so getting it from your vitamin C supplement shouldn't be a problem.

Sadly though, magnesium ascorbate is pricey compared to other forms of vitamin C. Rather than buy capsules I would suggest trying to find magnesium ascorbate powder. Dissolve an appropriate dose in water and take your other supplements with it.


@frian - Viridian are lovely supplements. They have an easy iron complex inc vit c but also have Ester-c formulas which appear to be your suggestion of magnesium ascorbate @humanbean


Hmm, don't think I've got that tagging right!

I've not tried these specific ones but have used other viridian stuff. Their Digestive Aid is great- I use as have no gall bladder and need to use digestive enzymes. Also good if have IBS etc.

No, I don't work for them lol.


I think Ester-C is usually calcium ascorbate.

Personally, I would prefer to take ascorbic acid than a mineral ascorbate. But if I had problems taking ascorbic acid I would take one of the mineral ascorbates instead (preferably magnesium ascorbate), rather than miss out on Vitamin C.


As far as the iron goes you are 7% of the way through the reference range. What more could you want? (I'm joking.)

Most of us feel at our best when we get closer to 50% of the way through the range.

I actually wonder if you have pernicious anaemia with a B12 result as low as yours. It needs to be around 1000 for most of us to feel well.

Do you take antacids or acid blockers?


I do take Gaviscon advance as and when I need to for acid reflux but not on a regular basis


Some info on low stomach acid and antacids. The scdlifestyle links are fairly short and to the point, the Chris Kresser links are longer and much more detailed.

Chris Kresser explains why problems arise in the first place :







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Have you also had Vit D and folate levels checked?

These need to be at good levels to and are often low.


yes vit D and folate are at good levels


Hi, personally, with levels as low as yours, I would do further testing before supplementing. methymalonic acid- MMA and homocysteine - hcy- should be your first port of call. These will indicate whether you are low at a cellular level- then your dr will have to take note - and at least put you on the loading doses followed by 3 monthly injections. You can additionally inject more after this point. Your dr should be able to do these tests but it is more likely you will have to do them privately. St Thomas hospital does them for eg.

As for vit D and folate at good levels- what are they at?

Look at the B12 deficiency website - some excellent info and read Sally Pacholok's book, Could it Be B12?


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