Massive hyperhomocysteinemia as a complication of nitrous oxide inhalation.

Here, we report two cases of venous thromboembolic events associated with massive hyperhomocysteinemia (7 to 10 fold the normal values) induced by a prolonged use of inhaled 50% nitrous oxide/oxygen premix during sickle-cell disease (SCD)-related acute pain disease. Given that SCD patients are at risk of deep vein thrombosis, we suggest that inhaled nitrous oxide should be use with caution in these patients and serum level of homocysteine should be monitored.