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Thyroid UK
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Confusing results

Hi All, I’ve had my blood tested this week and I must say I’m slightly confused.

In July my TSH was 1.00 ( 0.27-4.2. ) now it’s 4.89.

My FT4 was 23 ( 12-22 ) now it’s 18.6

Now I can see that it clearly shows I’m under medicated but I’m having trouble working out why it has changed so much in 6 months without changing my dose.

I am currently on 100mcg Levothyroxine so would it be wise to try 125 every other day or every day ?

My FT3 has dropped from 5.1 to 4.1 ( 3.1-6.8 )

Is it a seasonal thing ?

Any advice would be gratefully received and a merry Christmas to you all.

2 Replies


Thyroid function declines over time and more so if you have autoimmune thyroiditis (Hashimoto's).

TSH has risen because FT4 and FT3 have dropped. I would increase dose to 125mcg daily and retest in 6-8 weeks in case further dose increase is required.


Thanks Clutter, most helpful as always.


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