title: Metabolic cobalamin deficiency in patients with low to low-normal plasma cobalamins.
abstract: Over a 2-year period, we examined 48 patients with P-cobalamin levels in the difficult "grey zone" at the lower reference limit detected by a competitive protein binding assay using intrinsic factor as binder. In 21 of 30 patients (70%) with low P-cobalamins we could not establish the diagnosis of metabolic cobalamin deficiency, but 1 of 18 patients (6%) with low-normal P-cobalamin values was confirmed metabolically cobalamin-deficient. Half of these 30 patients with low P-cobalamins had neuropsychiatric disorders, but only one-third of the latter patients had metabolic cobalamin deficiency. Ten of the remaining 15 patients (67%) were characterized as non-deficient. In patients with low-normal P-cobalamin level, we found neuropsychiatric disorders in 5 of the 18 (28%), but none of these had metabolic cobalamin deficiency. We conclude that P-cobalamins below the reference interval combined with typical neuropsychiatric symptoms or findings are not diagnostic of cobalamin deficiency and that further analyses are necessary.
authors.affiliation: Department of Haematology and Clinical Chemistry, Aalborg Sygehus Syd (Aalborg Hospital), Denmark.
authors.forename: L
authors.initials: L
authors.lastname: Moelby
authors.forename: G
authors.initials: G
authors.lastname: Nielsen
authors.forename: K
authors.initials: K
authors.lastname: Rasmussen
authors.forename: M K
authors.initials: MK
authors.lastname: Jensen
authors.forename: K O
authors.initials: KO
authors.lastname: Pedersen
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000740:Anemia / Q000097:blood; D000748:Anemia, Macrocytic / Q000097:blood; D005260:Female; D006801:Humans; D008286:Malabsorption Syndromes / Q000097:blood; D008297:Male; D001523:Mental Disorders / Q000097:blood; D008875:Middle Aged; D009422:Nervous System Diseases / Q000097:blood; D011446:Prospective Studies; D014805:Vitamin B 12 / Q000008:administration & dosage / Q000097:blood* / Q000627:therapeutic use; D014806:Vitamin B 12 Deficiency / Q000097:blood*
chemical_list: D014805:Vitamin B 12