methylation, right on. i was asking the gp the other day about a histamine blood test because i seem to have symptoms of both over- and under- methylation (in terms of reactions to drugs and specific vitamins) he was pretty dismissive, so he would be even more opposed to testing homocysteine and SAMe levels. i might ask my new specialist doctor when i go back and get my labs from her.
Choline is your strongest methyl donor, followed by TMG, then DMG and finally SAMe. But TMG is safer than choline and can be taken at much higher levels.
however, none of these things really seems to explain this ridiculous systemic fluid retention. my hypothesis is that my body is diluting itself as a protection from oxidative stress due to liver dysfunction. i haven't found any information that would substantiate that though.
Fluid retention can be caused from a number of reasons. Adrenal issues are a common cause. It can also be from low potassium or problems with the heart, kidneys, nerves controlling blood vessels or lymphatic system. High vasopressin levels are another possibility.