L Carnitine and Thyroid function

[GettingAnswers]

My doctor has had me on L Carnitine for the past few weeks and I have gained 10 pounds and felt sluggish. I didn't make the potential connection until a moderator on a thyroid board said not to take L Carnitine if you are hypo and use it cautiously if normal, but it is good if hyperthyroid. Would love tosee if anyone has experience or thoughts on this potential link. The following abstract provides some insight



Effects of carnitine on thyroid hormone action.

AuthorsBenvenga S, et al. Show all Journal
Ann N Y Acad Sci. 2004 Nov;1033:158-67.

Affiliation
Abstract
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.

PMID 15591013 [PubMed - indexed for MEDLINE]

 

[Vettester Chris]

Interesting ... Janie at STTM has talked about L-Carnitine and magnesium to help with hyperthyroidism, and autoimmune instances like Grave's, but I haven't read much about it being antagonistic towards hypothyroidism. I'll do a little digging on this ...

 

[Nelson Vergel]

I could not find a single reference that links carnitine supplementation to weight gain in hypothyrodism.

I have taken 2000 mg per day for 15 years since it is shown to improve fatigue, muscle myopathy and liver function.

[h=2]l-Carnitine Supplementation to Diet: A New Tool in Treatment of Nonalcoholic Steatohepatitis—A Randomized and Controlled Clinical Trial[/b]Carnitine and Thyroid Disease

 

[GettingAnswers]

I haven't found any trials, just folks on thyroid forums stating it caused weight gain. This literature review alludes to it as well

http://m.news24.com/health24/Diet-and-nutrition/Weight-loss/L-carnitine-and-your-thyroid-20120721

I know it is likely coincidence but I have dropped three of the ten pounds I had put on in the past two weeks since stopping the carnitine....

 

[Brooksy Chuck]

does it interfere with thyroid medication absorption?i have seen conflicting info on this

 

[GettingAnswers]

I've only seen that it interferes at a cellular level with the uptake of the hormones. I haven't seen that it intereferes with absorption.

 

[Brooksy Chuck]

not sure what that means "uptake of hormones"? so it seems like since i am taking thryoid meds.. it would be ok to continue taking l carnitine? thanks!

 

[Justin Chile Farrar]

Broosky,

in my personal experience l-carnitine definitely slows down my thyroid and or messes with the absorption of my meds. I've read that in a few places and when I was taking a lot of carnitine I'd always feel really tired. Read the articles, stopped and feel better.