Oh Jane, what do you want to know....I have had six months of pernicious anaemia in my life and I know pretty much all there is to know.
It can be harmful as Sqad said only if undiagnosed. My partners hands became numb in October, doc said...carpal tunnel....come back in three months....couldn't wait three months as the legs from waist down joined in! Had two spells in hospital....still no diagnosis...he got a DVT (mid May) because he couldn't move very well. It was the Haematologist treating the DVT who asked how long had he had pernicious anaemia....we said 'is that what it is?' Almost certainly he said and he now uses my partner as a subject in his teaching as it is unusual to get this bad without being diagnosed. He is now fully loaded with B12 and having his next in September unless he feels he needs it sooner. The change is unbelievable, although he still has the neuropathy (numbness) it is getting better slowly. He was so poorly prior to seeing the Haematologist, hadn't eaten for three weeks and hadn't drank anything properly for a week because he couldn't keep it down, I truly believe I was a day or two from calling an ambulance....thank God for the DVT!
I hope you do not suffer the imcompetence we have Jane...and Sqad before you wade in defending the NHS, I can say this because the Neurologist in question has since written to us apologising for their imcompetence at diagnosing him, promising never to let it happen again.