Methoxyhydroxyphenylglycol (3,4)

Methoxyhydroxyphenylglycol (3,4) or 3-Methoxy-4-hydroxyphenylglycol (MHPG, MOPEG) is a metabolite of norepinephrine degradation. In the brain, it is the principal norepinephrine metabolite. It is released into the blood and cerebrospinal fluid, and a blood sample of it may therefore be an indication of recent sympathetic nervous system activity.