Thyroid UK

Recent blood results. Advice please, also puzzled about Active B12 result


Please could someone comment on my recent result.

In September Endo said to increase from 100mcg to 150mcg levo in one go. I did not want to increase by the 50mcg so increased to 125mcg for 5 weeks then increased to 150mcg for 5 weeks.

I then started getting really severe palpitations, racing pulse and internal shaking. Went to G.P. and she said go back to 125mcg.

Had bloods taken 2 weeks later and saw endo just before Christmas for results.

TSH 0.05 range 0.35 - 4.7

T4 13 range 7.8 - 21.0

T3 4.4 range 3.8 - 6.0

Appt. in December, Endo's registra asked how I had got on with increase, I explained the severe pals.etc. and she said I am not surprised as my TSH is suppressed. I replied but my T4 And T3 are not at top of the range, her reply was 'they are in range' I said they should be in top end of range to feel well. She just looked at me and said if you felt better on 100mcg go back to that. I said I felt better on the 125mcg, her reply, take 100mcg and alternate with 125mcg

In the meantime I have received my result for my Active B12 test from St. Thomas

Level 107 range 25 - 108 whilst I should be happy about this I am quite puzzled as in May this year the serum B12 result was 377 range 180 - 1130. I started supplementing with sublingual 2400iu daily but stopped 8 weeks before I had the active test. I really thought that as the serum test was low that the active would have been lowish also.

Can any please advice on either the thyroid or the B12 results.

Many thanks browny

2 Replies

If you felt good/better on 125mcg stick with it until your next test. If palps resume alternate 125/100mcg. The FT4 & FT3 serum results may be in range but may take longer to be felt intracellularly.

Serum B12 is notoriously inaccurate. The active test is the one to trust. The 6 months you were supplementing obviously paid off. I believe it isn't possible to overdose on B12 anyway :)



Many thanks for your reply, yes I am going to take the 125mcg. Do you know if the B12 supplement would have rose and stayed in my systems even though I was off the supplement for 8 weeks before the active test


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