Early sign of conversion problem?

Between pregnancies I lost close to 3st / 42 lbs / 19kg. Prior to my first pregnancy I was taking 150mcg but what I couldn't understand was that as the weight came down, my thyroid dose needed to stay the same; I'd always been given to understand that as one loses weight one generally needs to take less T4. Is it possible that this was the first sign of a conversion problem? I have no fT3 results from then, only fT4.

Just wondering...

5 Replies


As I understood it Levothyroxine was dosed first by weight and then by symptoms so I would have expected your dose to decrease as well.

There are many reasons why you are needing the extra T4 and without all thyroid hormones being tested it would be difficult to see the whole picture.

Do you feel under or over medicated now?


Possibly under: frequently cold, tired, easy weight gain if I don't keep an iron grip (although that may also be my insulin resistance at play). My last tests showed a high-normal fT4 with low-normal fT3.

Insulin resistance would not only make you inclined to weight gain but also interfere with thyroid med absorption.

Do you have low/high cortisol levels as well?

I suggest you post your lab test results complete with ranges (numbers in brackets) in a new question for members to comment.


Low TSH, high FT4 and low FT3 is a sign of bad conversion. Which would explain why you have easy weight-gaing, and feel cold and tired. You would probably do better with a bit of T3 added to your levo. :)

Hose, weight/dose is really only estimated for the initial dose after thyroidectomy/RAI. Thereafter dosing is guided by thyroid levels.

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