**5. Homocysteine and COPD and oxidative stress**

The first study to find a difference in homocysteine in COPD patients was reported by Andersson and colleagues (Andersson 2001). They examined the plasma from 19 patients with COPD and 29 healthy subjects. They found that total plasma homocysteine levels were higher in COPD than controls. But also that there was a decreased concentration of reduced glutathione and decreased reduced to total glutathione ration nine COPD. They speculated on a relationship between HCY as a surrogate marker of extracellular pro-oxidant activity and plasma homocysteine.
