title: Fasting time and vitamin B12 levels in a community-based population.
abstract: OBJECTIVE
  Vitamin B12, also known as cobalamin (Cbl), is an essential vitamin that manifests with numerous severe but non-specific symptoms in cases of deficiency. Assessing Cbl status often requires fasting, although this requirement is not standard between institutions. This study evaluated the impact of fasting on Cbl levels in a large community-based cohort in an effort to promote standardization of Cbl testing between sites.
  
  
  METHODS
  Laboratory data for Cbl, fasting time, patient age and sex were obtained from laboratory information service from Calgary Laboratory Services (CLS) for the period of April 2011 to June 2015. CLS is the sole supplier of laboratory services in the Southern Alberta region in Canada (population, approximately 1.4 million). To investigate potential sex-specific effects of fasting on Cbl levels, males and females were analyzed separately using linear regression models.
  
  
  RESULTS
  A total of 346,957 individual patient results (196,849 females, 146,085 males) were obtained. The mean plasma Cbl level was 386.5 (±195.6) pmol/L and 412.0 (±220.8) pmol/L for males and females, respectively. Linear regression analysis showed fasting had no significant association with Cbl levels in females; however a statistically significant decrease of 0.9pmol/L/hour fasting (p<0.001) was noted in males.
  
  
  CONCLUSIONS
  The broad population variance in Cbl suggests the slight gender-specific differences noted in this study are insignificant. Despite this, fasting has the potential to contribute to higher rates of Cbl deficiency in men. Together, these data suggest fasting should be excluded as a requirement for evaluating plasma Cbl.
authors.affiliation: Calgary Laboratory Services, Room C-156, 1st Floor Diagnostic and Scientific Research Centre, #9 3535 Research Rd. NW, Calgary, AB T2L 2K8, Canada.
authors.forename: Dennis J
authors.initials: DJ
authors.lastname: Orton
authors.affiliation: Calgary Laboratory Services, 4th Floor Diagnostic and Scientific Research Centre, #9 3535 Research Rd. NW, Calgary, AB T2L 2K8, Canada.
authors.forename: Christopher
authors.initials: C
authors.lastname: Naugler
authors.affiliation: Calgary Laboratory Services, 4th Floor Diagnostic and Scientific Research Centre, #9 3535 Research Rd. NW, Calgary, AB T2L 2K8, Canada. Electronic address: Hossein.Sadrzadeh@cls.ab.ca.
authors.forename: S M Hossein
authors.initials: SM
authors.lastname: Sadrzadeh
mesh_terms: D005215:Fasting / Q000097:blood*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D013997:Time Factors; D014805:Vitamin B 12 / Q000097:blood*
chemical_list: D014805:Vitamin B 12
keywords: Cobalamin; Fasting; Vitamin B(12)