title: The effects of nitrous oxide on vitamin B12 and homocysteine levels in methyltetrahydrofolate reductase gene mutation.
abstract: BACKGROUND
  We aimed to investigate the effects of nitrous oxide on plasma total homocysteine and vitamin B12 levels in patients with or without methyltetrahydrofolate reductase (MTHRF) gene mutation.
  
  
  METHODS
  After obtaining the ethics committee approval and written informed consents of patients, 93 patients between 18-70 years of age scheduled for surgery anticipated to last 1-4 hours were enrolled in the study. Patients with contraindications for nitrous oxide use were excluded. Preoperatively, blood samples were obtained from all patients for the determination of MTHFR gene mutation. Anesthesia induction was achieved with 3 mg.kg-1 of propofol and 1 µg.kg-1 of fentanyl. Anesthesia maintenance was performed with sevoflurane and with a carrier gas composed of 40 % O2 and 60 % N2O. Venous blood samples were obtained after venous canulation, and 24 hours after extubation for the analysis of plasma total homocysteine, vitamin B12 levels.
  
  
  RESULTS
  Eighty-one patients were included in the study. Postoperative vitamin B12 levels were found to be significantly lower when compared with their preoperative levels (p<0.05). It was found that MTHRF gene polymorphism had no significant effect on postoperative plasma total homocysteine and serum vitamin B12 levels (p>0.05). Postoperative plasma total homocysteine levels were found to be significantly different between patients with operation times under and over 3 hours (p=0.028).
  
  
  CONCLUSIONS
  We conclude that MTHRF gene polymorphism had no significant effects on postoperative plasma total homocysteine levels. However, we found that homocysteine levels might rise in patients who received general anesthesia with nitrous oxide for longer than 3 hours (Tab. 7, Ref. 26).
authors.affiliation: Department of Anesthesiology and Reanimation, Zonguldak Karaelmas University, School of Medicine Zongdulak, Turkey.
authors.forename: S
authors.initials: S
authors.lastname: Hakimoglu
authors.forename: V
authors.initials: V
authors.lastname: Hanci
authors.forename: Y
authors.initials: Y
authors.lastname: Hakimoglu
authors.forename: S
authors.initials: S
authors.lastname: Cicek
authors.forename: S
authors.initials: S
authors.lastname: Yurtlu
authors.forename: R D
authors.initials: RD
authors.lastname: Okyay
authors.forename: H
authors.initials: H
authors.lastname: Ayoglu
authors.forename: M
authors.initials: M
authors.lastname: Can
authors.forename: G
authors.initials: G
authors.lastname: Mungan
authors.forename: A
authors.initials: A
authors.lastname: Dursun
authors.forename: I
authors.initials: I
authors.lastname: Turan
mesh_terms: D000328:Adult; D004311:Double-Blind Method; D005260:Female; D006710:Homocysteine / Q000097:blood*; D006801:Humans; D008297:Male; D042965:Methylenetetrahydrofolate Reductase (NADPH2) / Q000235:genetics*; D008875:Middle Aged; D009154:Mutation; D009609:Nitrous Oxide / Q000494:pharmacology*; D011110:Polymorphism, Genetic; D011446:Prospective Studies; D014805:Vitamin B 12 / Q000097:blood*
chemical_list: D006710:Homocysteine; D042965:Methylenetetrahydrofolate Reductase (NADPH2); D009609:Nitrous Oxide; D014805:Vitamin B 12
keywords: Keywords: nitrous oxide, general anesthesia, homocysteine, vitamin B12, methyltetrahydrofolate reductase.