https://asbmr.onlinelibrary.wiley.com/doi/full/10.1002/jbmr.3226 check for HPP , abnormal high level of B6 can indicates you have that. Check your Protein Electrophoresis ( blood test)
Just one caveat -- there is only one person pushing this MTHFR thing, the naturopath Dr. Lynch. He is not an MD, which doesn't mean he doesn't know what he's talking about but MDs do not agree with him. Again, I'm no expert on this and only researched it because someone who posts on here occasionally mentioned this and I researched it for myself. What I learned is that while there are several common genetic mutations that affect methylation, almost nobody shows any signs of actually having a problem with it. Again, as I understand it, the problem shows as far as MDs are concerned as a homocysteine problem, which is an oxidation problem that is one suspected indicator of heart disease. This is controlled by the combination of B6, B12, and folate when in proper balance, and you will see in what are called homocysteine supplement formulas. There is no natural form of folate to supplement with -- they are all synthetic, man-made substances, which doesn't mean they don't work. Lots of supplements used in medicine are man made. The main thing is, it's rare for these defects to actually cause a problem that is discernible, and the only dissenter out there seems to be Dr. Lynch. Is he right? I have no idea. The training naturopaths get is quite different than what MDs get, and genetic mutations are definitely not an area that naturopaths would be expert in unless they learn it on their own. Maybe Dr. Lynch has, and maybe he hasn't. It's always hard to tell who has truth and who is trying to make money and sell books. It's definitely worth looking into for you, but I'm standing by my opinion that you're going to need to see unusual specialists who will really look into this as it could be caused by any number of things, and you seem to have an inordinate number of things that have "caused" your symptoms, such as iodine and antibiotics, and because your symptoms come and go. Look into everything, but realize that not all information is factual information and that most "genetic" problems aren't. We just aren't that far along in tying health problems to genetic markers at this point (and I'm not sure we really want to go all the way there, anyway, for ethical reasons of evolution vs. people believing they can make a better human). Look into everything, but with your logic intact -- as I said, if you do take methyl folate and you don't actually need it, it can cause problems for you, which Dr. Lynch does warn about on his website.
I found an article from the mthfr website - MTHFR C677T Mutation: Basic Protocol by Dr Lynch which is very informative on lifestyle and supplements. If you can't find this article let me know and I'll send you the link. One supplement mentioned is homocysteX which contains 800 mcg of methylfolate, 1000 mcg of methylcobalamin and 25 mg of pyridoxal-5-phosphate.
Excerpt from Easy Immune System Health - Find Out the Real Reason
For Vitamin B6 Toxicity...
"The MTHFR gene is extremely common and can lead to a problem processing the B Vitamins, making people particularly susceptible to deficiency of B12, folic acid, and Vitamin B6. Ironically, in these cases, Vitamin B6 Levels and Vitamin B12 Levels will be HIGH, despite actually being a DEFICIENCY of these vitamins. This is because the vitamins build up in the bloodstream, where they are measured, but the vitamins can't get into the cells where they are needed.
“The finding of high vitamin B6 levels is consistent with
recent reports of low levels of [Vitamin B6]. This may
explain the functional need for high-dose
vitamin B6 supplementation in many
children and adults with autism.”
Pilot Study of a Moderate Dose Multivitamin/Mineral
Supplement for Children with Autistic Spectrum Disorder
Because of this, the solution to Vitamin B6 Toxicity in those who are taking no or little Vitamin B6 is to get tested for the MTHFR gene, and if positive, they will need to actually supplement with high doses of B Vitamins, despite having high levels, but in the proper forms that can be processed by the body.
In the case of Vitamin B6 toxicity, the ‘active’ form of Vitamin B6 known as P5P, also known as pyridoxal-5-phosphate. While in the case of Vitamin B12, the active form is known as Methylcobalamin B12. These forms are able to be processed by the body so that they get into the cells where they can be utilized for body processes.
Ironically, high B6 levels in blood will decrease and return to NORMAL when sufficient amounts of P5P are taken to remedy the deficiency. The solution to Vitamin B6 Toxicity if you have the MTHFR gene is to stop getting the synthetic forms of B Vitamins, and get the proper active forms the body requires, like that present in a P5P supplement, Methylcobalamin B12, and a MTHFR Safe Multivitamin and Mineral Supplement."
The heading says you have a B6 problem, but your text seems to imply you feel you've damaged yourself taking too many infrared saunas, so it's not completely clear what's happening. B6 neuropathy is a real thing. If your B6 is high, it's high for some reason -- it is perhaps an imbalance caused by folate or B12 levels, as these three B vitamins are in balance with one another in the body. Sometimes taking too much B12 and folate can lower your levels of B6, but you do need to learn from your medical professionals why your B6 levels are high, if in fact that's the case -- sometimes one test will show them high and the next a day later might not.