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Thyroid UK
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Low Blood Sugar - Taking T3

11.5 weeks ago I started taking T3 added to my T4. I reduced T4 from 125/150mcg on alt days to 100 mcg & began with 6.25 T3 increasing to 12.5mcg 2 weeks later & so on until now I'm taking 25mcg T3 & 100mcg T4. So far no real noticeable changes .. 23 yrs on T4 with many symptoms & diagnosis of CFS & Fibro .. sleep problems & weight gain so decided to try T3. Bought Paul Robinson's book for guidance.

Today my blood sugar is low to the point of me feeling faint .. I have been unwell with a virus & lost some appetite so today have did not have my green smoothie for breakfast. I have had a gf bagel with jam, (very unusual for me) a boiled egg, whole pot of soup & chicken salad & a banana & some raw almonds & some of the raw seedy nutty snack I made. Still feeling jittery & empty but not hungry.

I am puzzled, does this have anything to do with T3/4 changes .. I used to get a little like this when I was still menstruating but can't seem to eat my way out of this today. I have made a chicken & veg curry with chickpeas & beans for dinner.

Any ideas or helpful advice? Thanks :)

8 Replies

25mcg of T3 is equivalent to 100mcg of T4 it's four times as potent.

Does that help?


I've often read that T3 is three times as potent as T4 so opinions do differ.

Some insane endocrinologists declare T3 to be 14 times as potent as T4. I've never understood where that little snippet of insanity came from.


They are getting confused. For most purposes (not all) T3 is four times as effective. The body produces between 10 and thirteen times more T4. T4 however is much more potent for some liver functions.

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Would that suggest that the body needs T4? If on T3 only, could levels of T4 be insufficient for certain liver functions?


If you do a search for hypothyroidism and hypoglycemia you'll find loads of links about how they are related.

This link is a useful one (I like Chris Kresser's site, it has lots of interesting articles) and discusses both hyper and hypoglycemia :


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T3 accelerates metabolism meaning you use more carbs. It also potentially improves Insulin action. That likely means you have enough, or too much thyroid hormone. It could also be transient while your system stabilises.

What were you thyroid results before and after the supplements?



When I initially medicated T3, I felt hungrier and believe this to be the result of the speeding up of my metabolism as I also lost weight.

Keeping blood sugars balanced by eating regular meals of slow acting carbs and protein helped me feel full for longer. If you let yourself get hungry, you will be stressing worn out adrenals glands further. Feeling hungry after eating indicates insulin resistance.

I believe recovery is a cumulative result in the healing of the multiple health conditions that low thyroid hormones induces and can take a long long time (if ever totally, depending on how long we were left ill for).

I started T3 june 2015 and although have felt well for a while, my health still continues to improve month on month. Your 23 years is a long time to be on Levo if it didn't suit you so improvements may take a while to be felt.

A virus may affect how thyroid hormones are working and I know when I get a cold my appetite increases ten fold but you may be little over medicated as are now taking more thyroid hormone than before. Also there is thought that adding T3 often encourages extra conversion of the T4 so you end of with a little extra than the amount you are medicating. My dose amounts have reduced as I have gained wellness.

If your body can not utilise the extra hormone properly, it may be converting to an excess of RT3 and therefore keeping you unwell. Do you have any recent results to post complete with ranges (numbers in brackets) ? ? If you don't, it would be prudent to test including T3 levels, to see where you are, now you are on your supposed optimal dose.


Thanks Radd for your reply. I didn't take any T3 yesterday & have had a better day today, although falling asleep on sofa after work all week. I might reduce my T4 and see how I go, maybe it's taken until now for T3 to have any effect & I need to adjust my dose? Probably this virus has thrown me off course, it seems everything is such a balancing act. My last bloods were done in Feb & I'm reluctant to see GP as she is not involved in my T3 dosing. I imagine she may refuse to treat me if I don't follow her advice & treatment plan. It's early days & I don't believe I'm on an optimal dose yet. Did I mention I'm gaining weight which is unexpected.

Thanks again.


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