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Thyroid UK
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Muscle weakness

Hi everyone. I was diagnosed with severe hypothyroidism 3 weeks ago. TSH >100 free T4 2.1. The reason I went and got tested was because I’ve been experiencing muscle weakness, like my arms and legs are heavy even when doing small tasks like brushing my teeth, texting on my phone, driving etc. I’ve only been on Levo Thyroxine for 3 weeks and I know it takes a while to kick in but I’ve had no relief from symptoms. Has anyone else experienced this type of sypmtom? I’m just worried that it may be down to something else rather than the thyroid issue.

Also since starting the Levo Thyroxine I’ve managed to loose 6 pound in 3 weeks (I’m on weight watchers) whereas before starting meds I was struggling to loose half a pound a week. Is this normal? It’s surprised me as I’m only on 50mcg and assumes it would take much longer to show any effect .

Thanks for reading! X

3 Replies

Oh God I'm surprised you were alive on such low thyroid!!!

Lost weight is most likely water retention you had due to very low thyroid hormones. It's a good start but it's a long way still to actually get rid of thyroid fat.

Please retest your thyroid every 4 weeks until you reach optimal Levo dose. You will most likely need an increase and I kind of feel doctor didn't tell you that. Don't let them keep you under medicated for a year like some of the people I read about.

Please also check for Hashi as they don't routinely check for it. If you're Hashi you're most likely to have pernicious anemia so you'll need b12 injections.

I felt relief of some of the symptoms from Levo few days after starting it. I was severe like you but I also was half dead. I made sure I checked bloods for correct dosage every 4 weeks and increased appropriately.

You have very long way! But you'll get better and stick to this forum, great advise from a lot of people.



Pleased you have been diagnosed and started treatment. As you were so hypothyroid you will probably have mucin deposited in your soft tissues which gives the appearance of swelling. This will go reasonably quickly on commencement of treatment, but sadly body fat takes longer. 50 mcg is a starting dose and hopefully your gp has asked you to repeat blood tests at 6 weeks to monitor your response to treatment. It is also important not to exercise too much in the beginning as your body will not have enough of the active hormone t3 for your muscles to work properly so exercise at this stage prolongs muscle weakness and muscle wasting. It can take up to 6 m onths to reach optimal dose and longer for physical symptoms to resolve, you will have to be patient.

Has your gp tested for peroxidase antibodies to see if you have autoimmune hypothyroidism, hashimoto’s disease.? If not ask at the next blood test. If it is positive there is a lot to read and learn.

Others will respond to your post. You will get much better, many people do well on levothyroxine, please don’t despair it just takes time.


It's seems that the people that get diagnosed with very high TSH can often react well and quickly to thyroid hormone replacement (Levothyroxine)

Assume you know to take Levo on empty stomach and then nothing apart from water for at least an hour after. Many take on waking, but it may be more convenient and possibly more effective taken at bedtime


Many people find Levothyroxine brands are not interchangeable. Once you find a brand that suits you, best to make sure to only get that one at each prescription.

You should be retested after 6-8 weeks and very likely to need dose further dose increase(s). 25mcg is maximum it should increase in one go

All thyroid tests should be done as early as possible in morning and fasting and don't take Levo in the 24 hours prior to test, delay and take straight after. This gives highest TSH, lowest FT4 and most consistent results

Do you also have high thyroid antibodies? You need to know. Did GP test these? If not ask that they are tested.

Very common to have low vitamin levels as result of being hypo

Good idea to also test vitamin D, folate, ferritin and B12. Always get actual results and ranges.

Post results when you have them, members can advise


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