Can anyone throw any light on why the 'normal' range of Vitamin B12 from a blood test has suddenly changed? It used to be 187-883 ng/L now the normal range is given as 51-128 ng/L. So....in Feb '22 a reading of 312 ng/L fell within the normal range. In July '24 a reading of 128 ng/L was said by the GP to be right at the top limit of normal. However, using the old 'normal' range a reading of 128 ng/L would be seriously low. It just doesn't seem to make sense. Any ideas??