Hi,I've been treated for hypothyroidism for about 8 years and for most of that time, taken 150mg of levothyroxine.
Recently, as the fatigue had become difficult after having covid, I found my B12 levels were low, so I started treatment for that. My fatigue improved about 2 weeks later.
I looked at my TSH values for recent years and they have been consistently low, around 0.1 so I'm wondering if I've been taking too much levothyroxine which was masking the B12 deficiency. And, as a result, if I should now try reducing the levothyroxine dose?
Any ideas please?
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CrochetDimples
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More likely poor conversion on Ft4 (levothyroxine) to Ft3 (active hormone)
For good conversion of Ft4 to Ft3 we need GOOD vitamin D, folate, B12 and ferritin levels
How low was B12
Can you add vitamin and thyroid results
Has GP tested for Pernicious Anaemia
Is your hypothyroidism autoimmune?
Recommended that all thyroid blood tests early morning, ideally just before 9am, only drink water between waking and test and last dose levothyroxine 24 hours before test
This gives highest TSH, lowest FT4 and most consistent results. (Patient to patient tip)
just testing TSH is completely inadequate
Bloods should be retested 6-8 weeks after each dose change or brand change in levothyroxine
For full Thyroid evaluation you need TSH, FT4 and FT3 tested
Also both TPO and TG thyroid antibodies tested at least once
Very important to test vitamin D, folate, ferritin and B12 at least once year minimum
About 90% of primary hypothyroidism is autoimmune thyroid disease, usually diagnosed by high thyroid antibodies
Autoimmune thyroid disease with goitre is Hashimoto’s
Autoimmune thyroid disease without goitre is Ord’s thyroiditis.
Both are autoimmune and generally called Hashimoto’s.
Low vitamin levels are extremely common when hypothyroid, especially with autoimmune thyroid disease
Oh wow, thank you. I'm going to need to answer properly later with all my results.For the moment, I'm 53, female, post menopause as I've had chemo which triggered it early, then later had a hysterectomy.
I've never been told if it's autoimmune or what type or cause of hypothyroidism. I don't think my thyroid antibodies have ever been tested.
It is taking some effort to get my head round this all. I have been rather lazy about it but realise that I can't do that in the current NHS climate.
I am not sure if I have been tested for pernicious anaemia. None of the tests mention it specifically and nor has my GP.
Looking back at test results, in December 2015, my thyroid peroxidase antibody level was 270 iu/mL which I think indicates that it is autoimmune? I don’t think TG thyroid antiboides have been tested for. What difference will it make if it is autoimmune?
On 9th Oct 2023: Serum TSH 0.09 mIU/L and Serum Free T4 26.2 pmol/L
On 15th Dec 2023: Serum TSH 0.11 mu/L
On 1st Dec 2023, private B12 test from Medichecks: 137 pmol/L which I think converts to 186 ng/L on 1st Dec 2023 Since then I have been taking very high dose B12 orally (2000 micrograms). I have also been taking Adcal (calcium and vit D for about 9 years.
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Blood results on T4/T3
picantaChicken 
Symptoms despite treatment 😩
TSH levels all over the place!
How to get T3? 
