title: Use of plasma methylmalonic acid in diagnosing vitamin B-12 deficiency in general practice.
abstract: OBJECTIVE
  To examine the reasons why general practitioners (GPs) request plasma methylmalonic acid (MMA) tests and how they respond to a result above the reference interval.
  
  
  METHODS
  Retrospective study of medical records.
  
  
  METHODS
  Primary health care, Aarhus County, Denmark.
  
  
  METHODS
  181 patients with increased concentrations of plasma MMA ( > 0.28 micromol/l) attending 10 GPs.
  
  
  METHODS
  Reasons for requesting the analysis and reactions to a plasma MMA level above the reference interval.
  
  
  RESULTS
  A reason for requesting plasma MMA was stated in 129 (71%) of the 181 medical records, screening being the most frequent. A reaction to an increased concentration of plasma MMA was recorded in 128 (71%) patients, and vitamin B-12 treatment was initiated in 102 (80%) of them. Among the 105 patients with marginally elevated plasma MMA level (0.29-0.44 micromol/l), vitamin B-12 treatment was initiated in 38 (36%).
  
  
  CONCLUSIONS
  Plasma MMA was frequently used as a screening test. Treatment with vitamin B-12 was initiated when MMA level was increased, and often when plasma MMA level was slightly above the reference interval. This strategy is likely to promote over-treatment with vitamin B-12.
authors.affiliation: Department of Haematology, Aarhus University Hospital, Denmark. am.hvas@dadlnet.dk
authors.forename: Anne-Mette
authors.initials: AM
authors.lastname: Hvas
authors.forename: Jørgen
authors.initials: J
authors.lastname: Lous
authors.forename: Jørgen
authors.initials: J
authors.lastname: Ellegaard
authors.forename: Ebba
authors.initials: E
authors.lastname: Nexø
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003404:Creatinine / Q000097:blood; D004909:Erythrocyte Indices; D004912:Erythrocytes / Q000737:chemistry; D005194:Family Practice / Q000458:organization & administration*; D005260:Female; D005492:Folic Acid / Q000032:analysis; D019983:Guideline Adherence / Q000592:standards / Q000706:statistics & numerical data; D006454:Hemoglobins / Q000032:analysis; D006801:Humans; D008297:Male; D008403:Mass Screening / Q000458:organization & administration*; D008764:Methylmalonic Acid / Q000097:blood*; D008875:Middle Aged; D018579:Patient Selection; D017410:Practice Guidelines as Topic; D010818:Practice Patterns, Physicians'; D011320:Primary Health Care / Q000458:organization & administration; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D014805:Vitamin B 12 / Q000097:blood; D014806:Vitamin B 12 Deficiency / Q000097:blood* / Q000175:diagnosis* / Q000628:therapy
chemical_list: D006454:Hemoglobins; D008764:Methylmalonic Acid; D005492:Folic Acid; D003404:Creatinine; D014805:Vitamin B 12