3-Methoxy-4-hydroxyphenylglycol (HMPG) is a metabolite of norepinephrine degradation in the brain. 3-Methoxy-4-hydroxyphenylglycol is an indicators of central nervous system noradrenergic activity. 3-Methoxy-4-hydroxyphenylglycol can be used for research of depression, chronic schizophrenia, etc[1].