Thyroid UK
84,221 members99,222 posts


Hi everyone I'm taking levothyroxine 100mg I've been on this medication with different mg for about 10 years I've never put weight on I'm quite petite always have been I'm quite confused to the effects that people have I struggle so hard to put weight on the only problems I get now and then are palpitations I'm seriously worried of can underlying problem as I have opposite to everyone else can some one give me some advice please thankyou

2 Replies

Hello, I'm exactly the same, in fact tend to loose weight when very hypo, gaining a little fluid when slightly.

I must say personally I've experienced mild palpitations when stressed and not quite on enough thyroxine.

Being petite I find small changes make a big difference - 125 is too little for me 150 too much so have to do alternate days.

It might be worth asking for a check - you may even be on top much, though I find I get sweaty and only sleep about 4 hours when like this. And very loose bowels.

Actually bowels are my clearest indicator of correct dose. If constipated im definitely not right, too loose and it's too much. Forgive the question but how do you feel?!

It *might* be something else though such as b12, folate, vit d (might be low this time of year as mainly get from sun April- sept) or ferritin. So worth checking with gp.

I've been diagnosed with hypermobility syndrome which is possibly why'd don't put weight on, certainly my muscles are very quickly and easily affected by low thyrixine ( within range) and recently found low ferritin too, they feel weak very quickly.

I guess heart is muscle so could be easily affected.


Welcome Mazmand

If you haven't had a recent blood test for your thyroid hormones, ask for one to be done. Take levothyroxine 24 hours before the blood test and take it afterwards. The test should be as early as possible.

Ask GP to take Vitamin B12, Vit D, iron, ferritin and folate as well as the thyroid blood tests. Get a print-out from the surgery with the ranges and post on a new question for comments from members. We are entitled to copies of our blood tests for our own records.

A few people don't gain weight (I didn't) but many do because they may not be on sufficient to raise their metabolism. So don't worry about not gaining weight.

All of our vitamins/minerals should be towards the top of the range.


You may also like...