title: Screening for vitamin B-12 and folate deficiency in older persons.
abstract: BACKGROUND
  Vitamin B-12 deficiency is usually accompanied by elevated concentrations of serum total homocysteine (tHcy) and methylmalonic acid (MMA). Folate deficiency also results in elevated tHcy. Measurement of these metabolites can be used to screen for functional vitamin B-12 or folate deficiency.
  
  
  OBJECTIVE
  We assessed the prevalence of vitamin B-12 and folate deficiency in a population-based study (n = 1562) of older persons living in Oxford City, United Kingdom.
  
  
  METHODS
  We postulated that, as vitamin B-12 or folate concentrations declined from adequate to impaired levels, tHcy (or MMA) concentrations would increase. Individuals were classified as being at high risk of vitamin B-12 deficiency if they had low vitamin B-12 (< 150 pmol/L) or borderline vitamin B-12 (150-200 pmol/L) accompanied by elevated MMA (> 0.35 micromol/L) or tHcy (> 15.0 micromol/L). Individuals were classified as being at high risk of folate deficiency if they had low folate (< 5 nmol/L) or borderline folate (5-7 nmol/L) accompanied by elevated tHcy (> 15 micromol/L).
  
  
  RESULTS
  Cutoffs of 15.0 micro mol/L for tHcy and 0.35 micro mol/L for MMA identified persons with normal or elevated concentrations. Among persons aged 65-74 and >or= 75 y, respectively, approximately 10% and 20% were at high risk of vitamin B-12 deficiency. About 10% and 20%, respectively, were also at high risk of folate deficiency. About 10% of persons with vitamin B-12 deficiency also had folate deficiency.
  
  
  CONCLUSIONS
  Use of tHcy or MMA among older persons with borderline vitamin concentrations may identify those at high risk of vitamin B-12 deficiency who should be considered for treatment.
authors.affiliation: Clinical Trial Service Unit, University of Oxford, Oxford, United Kingdom. robert.clarke@ctsu.ox.ac.uk
authors.forename: Robert
authors.initials: R
authors.lastname: Clarke
authors.forename: Helga
authors.initials: H
authors.lastname: Refsum
authors.forename: Jacqueline
authors.initials: J
authors.lastname: Birks
authors.forename: John Grimley
authors.initials: JG
authors.lastname: Evans
authors.forename: Carole
authors.initials: C
authors.lastname: Johnston
authors.forename: Paul
authors.initials: P
authors.lastname: Sherliker
authors.forename: Per M
authors.initials: PM
authors.lastname: Ueland
authors.forename: Joern
authors.initials: J
authors.lastname: Schneede
authors.forename: Joseph
authors.initials: J
authors.lastname: McPartlin
authors.forename: Ebba
authors.initials: E
authors.lastname: Nexo
authors.forename: John M
authors.initials: JM
authors.lastname: Scott
mesh_terms: D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D003404:Creatinine / Q000097:blood; D005260:Female; D005492:Folic Acid / Q000097:blood; D005494:Folic Acid Deficiency / Q000097:blood / Q000175:diagnosis / Q000453:epidemiology*; D006454:Hemoglobins / Q000032:analysis; D006710:Homocysteine / Q000097:blood*; D006801:Humans; D008297:Male; D008403:Mass Screening / Q000379:methods*; D008764:Methylmalonic Acid / Q000097:blood*; D015995:Prevalence; D012016:Reference Values; D012307:Risk Factors; D012737:Sex Factors; D006113:United Kingdom / Q000453:epidemiology; D014805:Vitamin B 12 / Q000097:blood; D014806:Vitamin B 12 Deficiency / Q000097:blood / Q000175:diagnosis / Q000453:epidemiology*
chemical_list: D006454:Hemoglobins; D006710:Homocysteine; D008764:Methylmalonic Acid; D005492:Folic Acid; D003404:Creatinine; D014805:Vitamin B 12