Table 1.

Sources and significance of plasma catechols and metabolites

Compound	Determinants	Significance
Norepinephrine	Sympathetic nerves	Sympathetic nerve traffic prognosis (e.g., heart failure)
	Uptake-1 activity	NET function
	Dopamine-β-hydroxylase	DBH deficiency
	LAAAD	LAAAD deficiency
	BH4	DHPR deficiency
		GTP cyclohydrolase-I deficiency
DHPG	VMAT/Vesic. Leakage	NE turnover
	NE reuptake	NET function
	MAO-A	MAO-A deficiency
		Familial dysautonomia
		Menkes disease
MHPG	DHPG	NE turnover
	COMT activity	Altered COMT function
MHPG-sulfate	MHPG
	SULT1A3
MHPG-glucuronide	MHPG	Hepatic function
	Glucuronidase
NMN	Adrenal medulla	Pheochromcytoma diagnosis
	Sympathetic nerves	Uptake-2 activity
	COMT activity	Altered COMT function
NMN-sulfate	NMN
	SULT1A3
VMA	MHPG	Hepatic function
	Alcohol dehydrogenase
	Aldehyde dehydrogenase
Epinephrine	Adrenal medulla	Distress
		Shock
		Glucoprivation
		Calorigenesis/obesity
		Asphyxia
MN	Adrenal medulla	Pheochromocytoma diagnosis
		21-Hydroxylase deficiency severity
MN-sulfate	MN
	SULT1A3
DA	Non-neuronal gut cells	Menkes disease diagnosis
	Circulating l-DOPA	DBH deficiency diagnosis
	Sympathetic nerves
DA-sulfate	Mesenteric organs	? Gastrointestinal TH activity
	Diet
	SULT1A3
DOPAC	Sympathetic nerves	TH activity
	MAO-A	MAO-A activity
	Extraneuronal MAO	Extraneuronal MAO activity
		Altered COMT function
HVA	COMT activity	Altered COMT function
	DOPAC
3-M-tyramine	COMT activity	Altered COMT function
3-M-tyramine-sulfate	3-M-tyramine
	SULT1A3
DOPA	Sympathetic nerves	TH activity
	Diet	LAAAD deficiency
		DBH deficiency
		DHPR deficiency
		GTP cyclohydrolase deficiency
	Melanocytes	Tyrosinase activity
		Malignant melanoma
	Extraneuronal TH	Neuroblastoma diagnosis
		Malignant pheo. diagnosis
3-MT	COMT	Altered COMT function
	DOPA
3-MT-sulfate	3-MT
	SULT1A3