I've been following Freddd's b12 protocol with initial success but had to put it on hold because I developed symptoms of electrolyte deficiency (or possibly surplus!). These symptoms have got worse since a virus (I now have occasional palpitations, left side slight chest pain, a feeling of slight breathlessness despite my breathing not speeding up, and facial twitching) and I need to go to my doctor to get them checked out. I hope it might be an opportunity to get magnesium supplementation by injection that I might not otherwise be offered; and/or monitoring of my electrolytes that will be helpful when I go back on the b12 protocol. I'd like to be able to show my doctor evidence that people with ME have b12 deficiency (so that he won't think I'm a nutter for supplementing with it) and magnesium deficiency. Several ME specialists seem to talk about both deficiencies and treat patients with supplementation for them but I'd like to be able to show my doctor a published research paper. In the UK, the standard NHS test for magnesium deficiency is a blood serum test. According to Dr Myhill, although a deficiency shows up first in the serum, it's not the most relevant measure because the body will take magnesium out of the cells to maintain the serum level to keep the heart going so you can be very deficient at the intracellular level. I gather that a test exists (in which country I don't know) for an intracellular test. Is there a research paper showing that this is superior that I could show my GP? Has anyone in the UK managed to get this test through their GP? Or privately?