title: Problems with the serum vitamin B12 assay.
mesh_terms: D001681:Biological Assay; D005056:Euglena gracilis / Q000187:drug effects; D056890:Eukaryota / Q000187:drug effects; D014805:Vitamin B 12 / Q000097:blood*; D014806:Vitamin B 12 Deficiency / Q000175:diagnosis*
chemical_list: D014805:Vitamin B 12