Nor-Adrenaline (Norepinephrine) Plasma test is used alongside plasma metanephrine measurements to aid in diagnosing pheochromocytoma and paraganglioma, and with urine vanillylmandelic acid tests for monitoring neuroblastoma. This test assesses norepinephrine, a key neurotransmitter regulating vascular tone, heart rate, and glucose metabolism, through its actions on alpha and beta adrenergic receptors.