title: Blood levels of homocysteine, folate, vitamin B6 and B12 in women using oral contraceptives compared to non-users.
abstract: OBJECTIVE
  To compare the levels of total homocysteine (tHcy), folate, vitamin B6 and B12, in women not using oral contraceptives (OC) vs. those using OC.
  
  
  METHODS
  219 healthy women were enrolled in the study; 159 of them had not been using OC for at least 12 months prior to their enrollment, while 60 were on regular OC treatment.
  
  
  RESULTS
  The median levels of vitamin B6 and B12 were significantly lower in OC users than in non-users (24.2 vs. 32.9 nmol/l, p=0.029; 278 vs. 429 ng/ml, p<0.001). There were no statistically significant differences in the levels of tHcy (fasting and post-methionine loading) and folate.
  
  
  CONCLUSIONS
  In our cross-sectional study, OC use was associated with low vitamin B6 and B12 levels. Since low vitamin B6 levels are independently associated with heightened risks for arterial and venous thromboembolism (TE), they could partly account for the increased TE risk of OC users.
authors.affiliation: A. Bianchi Bonomi Hemophilia and Thrombosis Center, Department of Internal Medicine, IRCCS Ospedale Maggiore, Italy.
authors.forename: Federico
authors.initials: F
authors.lastname: Lussana
authors.forename: Maddalena L
authors.initials: ML
authors.lastname: Zighetti
authors.forename: Paolo
authors.initials: P
authors.lastname: Bucciarelli
authors.forename: Massimo
authors.initials: M
authors.lastname: Cugno
authors.forename: Marco
authors.initials: M
authors.lastname: Cattaneo
mesh_terms: D000328:Adult; D003276:Contraceptives, Oral / Q000009:adverse effects*; D005260:Female; D005492:Folic Acid / Q000097:blood*; D006710:Homocysteine / Q000097:blood*; D006801:Humans; D008875:Middle Aged; D018570:Risk Assessment / Q000379:methods*; D013923:Thromboembolism / Q000097:blood* / Q000139:chemically induced*; D014805:Vitamin B 12 / Q000097:blood*; D025101:Vitamin B 6 / Q000097:blood*
chemical_list: D003276:Contraceptives, Oral; D006710:Homocysteine; D025101:Vitamin B 6; D005492:Folic Acid; D014805:Vitamin B 12