@TiddleTaddleTat he went into loads of detail about the condition- it was really interesting. He talked generally about things that can help - fluids, salt, compression gear, exercise protocol, etc. When I said that I was already doing a lot of that, he said yes, great, carry on.
The urine test is to check hydration levels but I'm intrigued about what the blood test is for. I already had a 7 day halter test, an Echo and ECG back in May so he's going to review those in the first instance. He said ideally that I should go to his clinic on 2 separate occasions for 2 different tests which I know I can't manage, so he said just try to go to the one more important one. I'm assuming that's the tilt table, and the other may be some kind of exercise/ stress thing which would finish me off!
I don't know if you use the Body Politic Slack forum but someone has recently posted a huge amount of really useful resources in the dysautonomia channel. I think the medics in NYC have been on to this far quicker than here in the UK.
Re diet, I've actually upped my milk uptake since starting as I'm now eating porridge every day. I've always been loathe to reduce dairy as I have osteopenia from the Coeliacs (and I'm at that age when it becomes more of an issue). I'll keep at it for a while longer but maybe add in the DOA supplements too.