L Carnitine reduces thyroid function: I came... - Thyroid UK

Thyroid UK

111,370 members129,502 posts

L Carnitine reduces thyroid function


I came across this article on Pub Med which will be of interest to those who are hypothyroid or those of us taking suppliments. In short L Carnitine reduces thyroid function. Who knew?

Effects of carnitine on thyroid hormone


By experiments on cells (neurons, hepatocytes, and fibroblasts) that are targets for thyroid hormones and a randomized clinical trial on iatrogenic hyperthyroidism, we validated the concept that L-carnitine is a peripheral antagonist of thyroid hormone action. In particular, L-carnitine inhibits both triiodothyronine (T3) and thyroxine (T4) entry into the cell nuclei. This is relevant because thyroid hormone action is mainly mediated by specific nuclear receptors. In the randomized trial, we showed that 2 and 4 grams per day of oral L-carnitine are capable of reversing hyperthyroid symptoms (and biochemical changes in the hyperthyroid direction) as well as preventing (or minimizing) the appearance of hyperthyroid symptoms (or biochemical changes in the hyperthyroid direction). It is noteworthy that some biochemical parameters (thyrotropin and urine hydroxyproline) were refractory to the L-carnitine inhibition of thyroid hormone action, while osteocalcin changed in the hyperthyroid direction, but with a beneficial end result on bone. A very recent clinical observation proved the usefulness of L-carnitine in the most serious form of hyperthyroidism: thyroid storm. Since hyperthyroidism impoverishes the tissue deposits of carnitine, there is a rationale for using L-carnitine at least in certain clinical settings.


15 Replies

What is this l carintine stuff. Is it in our food or medicines? Can we avoid it?

humanbean in reply to Hidden

I wouldn't want to avoid L-carnitine, but I wouldn't want to supplement it either (since I'm hypothyroid, not hyperthyroid). It does have positive uses within the body. According to wikipedia :

"In eukaryotic cells, it is required for the transport of fatty acids from the intermembraneous space in the mitochondria, into the mitochondrial matrix during the breakdown of lipids (fats) for the generation of metabolic energy"

Eukaryotic cells are cells with a nucleus, so basically, a huge proportion of the body's cells would be of this type.

Another reason for not eliminating it from the diet :

"In the course of human aging, carnitine concentration in cells diminishes, affecting fatty acid metabolism in various tissues. Particularly adversely affected are bones, which require continuous reconstructive and metabolic functions of osteoblasts for maintenance of bone mass. A 2008 study found that supplementing with L-carnitine decreased bone turnover and increased bone mineral density in rats."

Source : en.wikipedia.org/wiki/Carni...

Apparently, vegetarians are likely to get a lot less L-carnitine in their diet than non-vegetarians. I don't have the faintest idea whether this is a good reason for vegetarians to supplement though.

Its interesting as I am supplimenting with it for Fibromyalgia and I am hypothyroid. I am also taking L Tyrosine which helps T4 T3 conversion. I have noticed less aches and soreness in my arthritis as a side effect as well as improved fibro symptoms. I haven't had to increase my NDT nor have I noticed any increase in hypo symptoms so maybe the L tyrosine is counteracting the L Carnitine. Only 3 weeks into this new regime so still early days.

maggi999 in reply to lb003

It sounds like you are very well medicated for hypo and you are counter-acting one supplement with another!

If you don't mind me asking, what came first, the hypo or the fibro?

Maggie x

lb003 in reply to maggi999

Hi Maggie. I was diagnosed with Hypothyroidism first in my 40's however I now suspect that I was swinging between hypo hyper from my early 20's. The Fibro was diagnosed later but again I suspect that I had it for years. I am also gluten intolerant and the gut plays an important role in Fibro and thyroid problems, so that's no surprise. Not a straight forward answer I am afraid.

L-Carnitine can be used in the treatment of hyperthyroidism as, as Humanbean says, it is used for the transport of fatty acids in the body.

I suppose the advice should be, if you are hypo, don't supplement with L-Caritine, useless you are are having kidney dialysis or taking medication for seizures, then seek advise from your GP re monitoring levels.

I wonder whether acetyl-L-carnitine has the same effect as L-Carnitine...Dr Myhill recommends the former for people with chronic fatigue syndrome..Has anyone experience with using Acetyl-L-Carnitine? Thank you

lb003 in reply to Martina

I believe that acetyl-L-carnitin is hydrolyzed and so more usable in the blood. But don't quote me on that.

If you took L-Carnitine at least 4 hours after and before any thyroid meds, would it perhaps be okay to take L-Carnitine?

Thank you Ib003 i've been looking for something natural to help the hyper symptoms that seem to dominate me at the moment, so will research further to see if This is viable for me to try 🐯T

I'm a patient of Dr Myhill, who ran mitochondrial functions tests for me earlier this year. The results were very poor indeed, but one of the problems which was flagged up was a deficiency of acetyl l-carnitine. She recommended I supplement 1g per day of the powder, dissolved in water. I was a near-vegetarian for many, many years and only returned to regular meat-eating about three years ago. Even so, it wasn't enough to get my carnitine levels up within the normal range.

humanbean in reply to Hillwoman

Do you notice any improvement in health since supplementing?

Hillwoman in reply to humanbean

Difficult to say at present, since I have so many health problems, and my mitochondrial function is down to 23%. I've only been following Dr M's treatment programme and Dr Peatfield's revision to my thyroid and adrenal treatments for 2-3 months. It's taken me a long time to get this low, so it will to take a while for any improvements, I think!

I supplemented with this when I was hyper with Graves, I tried 3g but it made no difference to me.

lb003 in reply to Silver_Fairy

That fits with my experience in that it's not affecting me adversely and I am hypo.

You may also like...