title: Problems with B12 radiodilution assays.
mesh_terms: D003951:Diagnostic Errors; D006801:Humans; D011865:Radioisotope Dilution Technique; D014481:United States; D014486:United States Food and Drug Administration; D014805:Vitamin B 12 / Q000097:blood*
chemical_list: D014805:Vitamin B 12