title: Influence of age, sex and vitamin status on fasting and post-methionine load plasma homocysteine levels.
abstract: OBJECTIVE
  To investigate the effects of age, sex and vitamin status on total plasma homocysteine (tHCy), both after fasting (FtHCy) and two hours post-methionine load (PML-tHCy). The secondary aim was to determine the reference values for FtHCy and PML-tHCy.
  
  
  METHODS
  A cohort of apparently healthy volunteers underwent blood sampling for FtHCy, PML-tHCy, creatinine, serum folate, vitamin B12 and vitamin B6 (pyridoxal-5-phosphate, PLP).
  
  
  RESULTS
  In 147 subjects (M/F= 82/65, age range: 14-94 years), FtHCy was significantly higher in men than in women. In men, age and folate levels explained 20.5% and 19.0% of FtHCy variance, respectively. In women, age and vitamin B12 accounted for 22.6% and 17.8% of FtHCy variance, respectively. PML-tHCy was similar in men and women. PML-tHCy was negatively correlated with folate in both sexes, and with vitamin B12 and age in women only. Folate accounted for 20% of the variance of PML-tHCy in men, while in women vitamin B12 and PLP explained 40% and 20% of variance of PML-tHCy, respectively. The reference values of FtHCy and PML-tHCy were: 19.63 and 40.18 mol/L, respectively, for men under 45 years, 14.26 and 28.31 mol/L, respectively, for women under 45 years, 28.38 and 36.48 mol/L for men above 45 years, and 22.49 and 44.06 mol/L for women above 45 years.
  
  
  CONCLUSIONS
  Age, gender and vitamin status influence both FtHCy and PML-tHCy in normal subjects. Reference values should be calculated according to age and sex.
authors.affiliation: Cardiovascular Department, Central Laboratory, University Hospital S. Orsola-Malpighi, Bologna, Italy.
authors.forename: Simonetta
authors.initials: S
authors.lastname: Sassi
authors.forename: Benilde
authors.initials: B
authors.lastname: Cosmi
authors.forename: Gualtiero
authors.initials: G
authors.lastname: Palareti
authors.forename: Cristina
authors.initials: C
authors.lastname: Legnani
authors.forename: Gabriele
authors.initials: G
authors.lastname: Grossi
authors.forename: Serena
authors.initials: S
authors.lastname: Musolesi
authors.forename: Sergio
authors.initials: S
authors.lastname: Coccheri
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000097:blood*; D005215:Fasting / Q000097:blood*; D005260:Female; D006710:Homocysteine / Q000097:blood*; D006801:Humans; D008297:Male; D008715:Methionine / Q000008:administration & dosage / Q000494:pharmacology*; D008875:Middle Aged; D012727:Sex Characteristics; D013997:Time Factors; D014815:Vitamins / Q000097:blood*
chemical_list: D014815:Vitamins; D006710:Homocysteine; D008715:Methionine