Thyroid UK
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How often to check blood levels?

In the last week I've started taking Jarrow B12 and been on ferrous fumarate for around 3 weeks due to low ferritin and B12. As posted in other threads my TSH is 2.5 (0.3-4.5) and my T4 is 9.1 (7.0-17.0). My ferritin is 27 (15-300) and B12 is 233 (150-900).

I have felt dreadful for a few years, but steadily getting worse - cold, weak, dizzy, periods gotten shorter, tired etc and don't expect to feel right straight away but was wondering how long I should supplement before I try NTD? My Dr refuses to treat as my levels are 'normal' even though I don't feel anywhere near it!

Do I need another blood test in say 3-6 months time to check the levels? Also, those who self medicate, do you get regular blood tests or just go on how you feel as to your dosage?

4 Replies

FallenAngel, You need to supplement iron for 4/6 months before you can expect much improvement in ferritin because yours is very low. B12 may take around 2 months. It's not worth testing either for 4 months as this is the time it takes for old red blood cells to die off and new ones to replace them. Stop supplementing iron 2 weeks prior to a ferritin test. B12 usually shows high when one is supplementing. To get a baseline result you will need to stop supplementing 8 weeks prior to retesting.


Thank you that's really useful and helpful. Guess it's a long haul!


Have they done your antibodies? Or maybe not because you're 'normal' in other regards - ?

What are your feelings about private testing? You need to know if you have antibodies, because if you have Hashi's they're just waiting for your tsh to rise above 10 before you get meds and in the meantime you will feel very ill.

Did I read somewhere that you're having trouble w your iron supps? I use Solgar Gentle Iron and take it w two vit c caps and I have no stomach/gut issues with it at all (most iron makes me feel queasy). Good luck! Keep plugging away at it. x


Yes I struggle with iron (ferrous fumarate) so only take 1 a day which seems to be ok but obviously not as much as I should have. I sometimes have spatone too with orange juice. My hg levels are now out of anemia status but my ferritin is quite low (27).

I have no idea re antibodies - are they done as part of normal thyroid function screening do you know? I am back at the drs in a couple of weeks so will check and see if he will test. He definitely won't do T3 as I already asked. I don't have any issues with private testing but worry about legit places and the cost. Can you advise?

Many thanks!


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