I understand magnesium deficiencies are hard to detect in normal blood tests as the body will keep this fairly stable, and mine are fine in the nhs blood test for kidney troubles. I have explained all this to gp, but nhs only will do that one test and i don't qualify to see nhs nutritionist (i had hoped that might be a way to have blood taken to send to biolab) - how did other people check their mag levels? Oh to have unlimited funds and get all this seen to privately! But with a dad in the States, still very grateful for nhs! As i come slowly off the meds i'd like the back-up of some supplements, wish there was a natural health college nearby that needed some guineapigs! how do other people know they are low in magnesium?? I know the electrolytes are a delicately balanced bunch so don't want to cause myself more problems. When I stopped smoking i took up boiled sweets and burst a tooth, so i went for liquorice next instead of chocolate - those of you who saw it on tv know where that ended up! Too much can cause hypertension and therefore if you have arrhthymia you have to be careful.Although the manufacturers of my fav liquorice tell me the raspberry falvour one has a tiny amount of the problem ingredient, i am now experimenting with diff flavours of dark chocolate to have something for a treat. Anyway - the magnesium - how do you know your levels are low?