Homocysteine After Nitrous Oxide Anesthesia

This study has been completed.
Information provided by:
Medical University of Vienna
ClinicalTrials.gov Identifier:
First received: June 1, 2007
Last updated: NA
Last verified: May 2007
History: No changes posted

Our study looks at the interaction of a common mutation in the MTHFR gene and the risk of developing higher homocysteine levels after nitrous oxide (N2O) anesthesia.

Specifically, we want to test the hypothesis that healthy patients carrying the MTHFR 677C>T haplotype develop abnormal homocysteine levels after nitrous oxide anesthesia.

Condition Intervention Phase
Anesthesia, General
Adverse Effects
Nitrous Oxide
Drug: Nitrous oxide
Phase 4

Study Type: Interventional
Study Design: Endpoint Classification: Pharmacodynamics Study
Intervention Model: Single Group Assignment
Masking: Open Label
Primary Purpose: Basic Science
Official Title: Influence of the MTHFR 677C>T Mutation on Homocysteine Levels After Nitrous Oxide Anesthesia.

Resource links provided by NLM:

Further study details as provided by Medical University of Vienna:

Primary Outcome Measures:
  • Homocysteine levels dependent on MTHFR genotype [ Time Frame: 2 years ]

Enrollment: 140
Study Start Date: January 2005
Study Completion Date: March 2007
Detailed Description:

Nitrous oxide – laughing gas – is a widely used anaesthetic gas with many favourable but also some dangerous properties. Among the latter is the increase in homocysteine levels after nitrous oxide (N2O) exposure by inhibition of enzymes in the vitamin B12 pathway. Elevated homocysteine levels have been found to be an independent risk factor for ischemic events and are associated with an increased risk for perioperative myocardial ischemia. If a patient carries one or more loss-of-function mutations in enzymes of the methionine/homocysteine/folate pathway he is at an increased risk for hyperhomocysteinemia and if exposed to N2O might suffer severe, sometimes disastrous neurological damage. Recently, a case report in the New England Journal of Medicine reported the death of a child with an enzyme defect in the MTHFR gene after anaesthesia with nitrous oxide (NEJM 2003;349:45-50).

Thus, we are convinced that if we can determine the risk of patients who carry mutations in the MTHFR gene and undergo anaesthesia with N2O for developing pathological levels of homocysteine, we can add an important piece of information to the safety profile of N2O.

Our study tests the hypothesis that patients who carry the 677C<T mutation in the MTHFR gene (the most common mutation) have a higher risk of developing hyperhomocysteinemia after N2O anaesthesia.


Ages Eligible for Study:   18 Years and older
Genders Eligible for Study:   Both
Accepts Healthy Volunteers:   No

Inclusion Criteria:

  • Patient scheduled for general anaesthesia (> 2 hours)
  • Age > 18 years
  • ASA status I-II

Exclusion Criteria:

  • Pregnancy
  • Age < 18 years
  • contraindication against N2O: pneumothorax, mechanical bowel obstruction, middle ear occlusion, laparoscopic surgery
  • recent use of vitamin preps (B12, B6, folate)
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Please refer to this study by its ClinicalTrials.gov identifier: NCT00482456

Dept of Anesthesiology, Medical University of Vienna
Vienna, Austria, A-1090
Sponsors and Collaborators
Medical University of Vienna
Principal Investigator: Peter Nagele, M.D. Medical University of Vienna
  More Information

Publications automatically indexed to this study by ClinicalTrials.gov Identifier (NCT Number):
ClinicalTrials.gov Identifier: NCT00482456     History of Changes
Other Study ID Numbers: EK 286/2004 
Study First Received: June 1, 2007
Last Updated: June 1, 2007
Health Authority: Austria: Agency for Health and Food Safety

Keywords provided by Medical University of Vienna:
Nitrous oxide
vitamin B12

Additional relevant MeSH terms:
Nitrous Oxide
Analgesics, Non-Narcotic
Anesthetics, General
Anesthetics, Inhalation
Central Nervous System Depressants
Peripheral Nervous System Agents
Physiological Effects of Drugs
Sensory System Agents

ClinicalTrials.gov processed this record on May 22, 2016