Thanks triffid. Yes you are right. I am actually pretty well versed in NMDA receptor activity given my rare autoimmune disease. You can search on these forums, I have a number of posts discussing with others (especially Adreno) about NMDA receptor activation and various agonists and antagonists. I also think one overlooked aspect is the localized control of glycine and other various cofactors around the neurons on a dendritic branch. That is why blanket generalization about certain molecular entities is dangerous (i.e. "if I take glycine it will automatically activate my NMDA receptors" -- not correct). But yes I get 1600 mg of magnesium a day for just that reason Estrogen protection is good, but the correlation between estrogen levels in the serum and what is in the brain is not as tight as the medical community would like you to believe. The best test is ultrasensitve estradiol. Anyways in my other posts there are many other ways to handle glutamate activation of the NMDA receptors. I think my concerns with ammonia are not that I am anywhere near out of range, but more the fact that the more load the ammonia puts on BH4 the less BH4 I have for NO, peroxynitrite removal, neurotransmitters, the urea cycle, etc.