I have been diagnosed with hypothyroidism and am being treated with Levothyroxin. While my TSH levels now come back as normal, I am still experiencing symptoms such as fatigue, muscle weakness, focus issues, etc. I am waiting to get in to see an endocrinologist for a second opinion.
In the meantime, I tried a workout supplement containing L-Arginine. I found that on days that I used the supplement, most of those symptoms were lessened or disappeared entirely. I thought that might be more than a coincidence, so I tried to research the issue and discovered that the thyroid is involved in converting L-Arginine into Nitric Oxide. I could not, however, find anything suggesting that taking an L Arginine as a supplement could be helpful with those suffering from sub-clinical hypothyroid (or any thyroid issues for that matter).
So, is my improvement while using this coincidental? Is there a relationship between hypothyroid and NO deficiency? Is there any reason not to continue taking the L Arginine?
First of all I think your Levothyroxin isn't the right medicine for hypothyroids, since it's only T4 (and not also T3).
Second, I think you're right. Arginine blocks the effect of somatostatin. Somatostatin makes the hypothalamus "go very slow", therefore lowering growth hormone, cortisol, thyroid, etc.
Probably your symptoms fall under the category "chronic fatigue syndrome", right? Maybe you also have food allergies? Taking thyroid medication doesn't solve the problem, perhaps only T3 medication in large quantities does.
I think the problem is that arginine is a semi-essential aminoacid, meaning that in stressfull situations the human body can't make enough of it itself. And since we don't eat what our bodies were used to for centuries, nuts and seeds which contain a lot of arginine, many of us have a deficiency of arginine. Arginine deficiency is therefore a known issue in CFS.