UK NEQAS, the body which ensures the quality of UK lab results, have publicised their concerns over the traditional B12 tests. In the April 2013 newsletter of the Association of Clinical Biochemists (ACB), they write:
“UK NEQAS Haematinics is keen to publicise their concerns on problems with current B12assays which may be vulnerable to interference resulting in normal values despite severe cobalamin deficiency.
The Committee advises that where there is a discordance between the clinical features of neuropathy such as parasthesiae, loss of joint position sense, or megaloblastic anaemia and a “normal” B12 result, clinicians are advised to request storage of serum for further testing and are advised to treat the patient withB12 replacement therapy.
Further testing may include repeat testing by an alternativeB12 assay, holotranscobalamin assay, serum methylmalonic acid and measurement of intrinsic factor antibody. Treatment with B12 should not be delayed to avoid progression of neurological damage”
View the warning in the ACB newsletter here.