Thyroid UK

Muscle spasms ?

Hi, I`m getting ongoing painful muscle spasms in my lower back but strangely only on the left side?

I had RAI 2 yrs ago, my latest blood results showed TSH 0.27 (0.35-3.50) T4 19 (8-21).

My levo was reduced 3 months ago and since then I`ve felt fine with my weight and energy at last back to pre RAI but the ongoing problem has been these spasms.

The spasms are a bit better to what they were and I`m wondering if it may help to reduce the levo just a tiny bit more...say 25 mcg per week?

Can too much levo cause these spasms? If I could tackle this I`d be so grateful ...thanks

1 Reply

I had all sorts of muscle spasms, cramping and twitching. I rarely suffer now. The things which made the difference for me are :

1) Supplementing my low iron to get all iron-related measures up to optimal (or as close as I could get them anyway). All sorts of things are affected by low iron :


serum iron

transferrin saturation

total iron binding capacity



red blood cell count

There may be others, but those are the ones I remember. To get all these tested you would need an iron study (or iron panel - the name can vary), plus a full blood count. Your doctor may do these tests for you if you ask, or may have done them recently. If this is the case then get a copy of the results and reference ranges, post them in a new question, and ask for feedback.

Alternatively, these tests can also be done privately with a finger prick test :

2) Supplementing magnesium. There are lots of different kinds of magnesium supplement and people have to pick the one that works for them. Practically everyone on the entire planet is deficient in magnesium. Avoid magnesium oxide, it is very poorly absorbed.

Some forms of magnesium supplement make people sleepy so should be taken before bed. Some forms of magnesium supplement are mild laxatives, which may or may not be helpful. Experiment to find what works best for you.

3) Potassium. Only supplement potassium if nothing else works. It should be taken very cautiously. Too much potassium will affect the heart rhythm. Personally, I take 2 x 99mg potassium just before bed and it helps my muscles to relax. There is a connection between taking high dose Vitamin B12 and low potassium in some people, but this doesn't affect everyone :


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