0 NE and E (in Pheochromocytomas)

About 50% of adrenal pheochromocytomas produce near exclusively norepinephrine, this representing the same pattern as in extra-adrenal pheochromocytomas.

Production of epinephrine (best detected by an increase in metanephrine) indicates an adrenal location,

exclusive production of norepinephrine (best indicated by increases of normetanephrine with normal metanephrine) may reflect either an adrenal or extra-adrenal location.

Practically all epinephrine-producing pheochromocytomas are found in the adrenal gland or are recurrences of previously resected adrenal tumors.

All of the catecholamines are broken down into inactive substances that appear in the urine:

• Dopamine becomes Homovanillic acid (HVA)
• Norepinephrine becomes normetanephrine and vanillylmandelic acid (VMA)
• Epinephrine becomes metanephrine and VMA

Effect	Epinephrine	Norepinephrine
Heart rate	increases	decreases
Cardiac output	increases	variable
Blood pressure	increases	increases
Respiration	increases	increases
Metabolism	increases	small increase
Behavior	passive, tense	aggressive
Eosinophil count	increases	----
Skin blood vessels	dilate	constrict
Muscle blood vessels	dilate	small dilation