I am in the UK and been told I am defficient, take 20, 000ui d3 3 times a week for 8 weeks then I have to take desunin d3 800 twice daily for ever. Had 2 doses so far and feel rubbish. I know there is a kicking in time but come on why can't Doctors start us off at a lower dose so as not to shock our systems! My question is should I he taking any other vitamin or ??? to help it do its thing? Do I up my water drinking, have calcium or magnesium? Just being told here you are deficient take these tablets and you will feel better is rather simplistic. Have to say I am relieved its not tumours on my parathyroid thingy as high calcium levels, low vit d and a low pth level might show that if I remember rightly. I have a 13.3 pth (high) vit d less than 30 nmol/L and calcium 2.18 (low) am also surprised they didnt say my ferritin was low as our ranges are 20-291 and mine is 25 trying to understand all this is mad. I know ranges differ between the UK and US but do I take anything else like multi vits but then even they have vit d and I really dont want to take any more. Arghhhhh so confused. Panic attacks are on an all time high too. :( any advice would be gratefully received. Thanks.