There are so many things that could be changed.
Just looking at thyroid issues - the country uses reference ranges that have not altered in decades, and vary from one area to the next.
In Manchester, I was just inside the range = not suffering hypothyroid, the symptoms therefore must be in my head/something else.
In West Midlands, I am outside the referenge range = am hypothyroid, the symptoms are those of hypothyroidism, I am treated for it and am much better.
HOW can I be ill in one county and not in the next?
The answer is that these 'treat by numbers guidelines' that GP's are given, are not guidelines, they are 'stick to these rules or else' - GP's who think outside the box, treat the symptoms not the numbers, are sticking their necks on the line and thats not a safe thing to do for most of them.
B12 deficiency is a similar issue - according to the numbers, I have enough b12 in my blood, therefore the symptoms of b12 deficiency are in my head/something else/go away.
However those numbers don't indicate whether I am using that b12, they don't actually know if that amount of b12 is right for me (again those reference ranges are hugely outdated) - and whaddya know, treated with B12, those symptoms go away.
I have to supply and administer my own b12, because the 'guidelines' state if the tests suggest a deficiency, you get a jab once a month for three months then one every three months... That isn't sufficient for me, I need 2ml once a week, if I miss a dose... I start going fucking blind (seriously, my vision goes really fuzzy, to the point after a day or two, I can't see my phone screen or watch tv, never mind read the computer screen).
Because I am unwilling to go blind for long enough for the NHS to stick me on waiting lists, do tests, find out why i need huge amounts of B12... whatever the underlying issue is will remain undiagnosed.
I am not stopping taking the B12 and putting my trust back in them to find out as they've expressed no interest in doing so, and when pushed made it very clear it would require six months minimum off the B12 and its all my own fault for taking it without their say so.