Thyroid UK
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Under active thyroid

This is my first post and want to ask a question.

Was quite surprised to be diagnosed with under active thyroid because I had no symptoms whatsoever, I have been on Levothyroxine 150mcg for a very long time. Earlier this year I was diagnosed with Type 2 diabetes and take Metformin. I have been on a Low Carb/Higher Fat diet since then and have lost over a stone in weight and my BG levels are down to six. My thyroid test was 0.33 miu/L in February 2015 and my last blood test in August was less than 0.1 miu/L and my meds have been reduced to 100mcg.

Does anyone have any idea why my thyroid is improving. Have another blood test in 6.8 weeks and will see what happens then.

Thank you Carol

5 Replies

Welcome to the forum, Redrow.

Metformin can reduce TSH without affecting FT4. Low TSH when FT4 and FT3 are within range does not indicate overmedication. I think your GP may have reduced dose too aggressively. If you start feeling hypothyroid ask for dose to be increased by 25mcg.

Thyroid function and blood sugar levels should be carefully monitored when either Levothyroxine or Metformin dose is adjusted.

Levothyroxine may reduce effectiveness of Metformin. Try to take them at least 4 hours apart.


Thank you for your reply. As I didn't have any symptoms originally I don't know what to look for in hypothyroid. I can only go by what the Doctor says and she didn't have an answer when I asked why my figures have reduced, she just said it happens sometimes.



Redrow, fatigue, weight gain, hairloss, feeling cold, muscle aches and pains are probably the most common.


No, never had any of those symptoms.


Check the Thyroid UK site for a list of symptoms.

I know someone who attended a well woman clinic about 20 years ago and was found to be hypothyroid and treated but has never had any symptoms.

Apparently it can take decades for symptoms to appear so catching it before they do must be good.


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