Catecholamines (noradrenaline, adrenaline and dopamine) are adaptive and maladaptive stress hormones.~In the classic fight or flight mechanism, they activate behavioral and physiological processes that facilitate the overcoming of stress; for instance, challenged by a physical stressor, an organism responds to the threat either fighting and prevailing or accepting defeat and fleeing in avoidance.~In the pathological context, an excessive catecholamine secretion is typical of the chromaffin tissue tumors, determining a clinical picture characterized by blood pressure elevation, tachycardia, anxiety, pallor, sweating and headache.~COMT enzyme catalyzes the O-methylation of the 3-hydroxyl group of catecholamines. The O-methylated derivatives of noradrenaline, adrenaline and dopamine are normetanephrine, metanephrine and 3-methoxytyramine, respectively. The term metanephrines is generally used to collectively refer to the first two compounds.~Compared to catecholamines, metanephrines are characterized by longer half-life and more stable levels over time. Their superior accuracy for the diagnosis and follow-up of pheochromocytoma and paraganglioma (PPGL) has been widely proved.~Excluding patients with PPGL, however, metanephrines can be more broadly considered as reliable markers of the whole sympathetic system activity; therefore, their levels may be hypothesized to be associated to a higher rate of concurrent cardiometabolic complications and, if so, could be useful for the stratification of cardiovascular risk.
Recent studies on catecholamine physiology have shown a direct correlation with arterial hypertension, overcoming the exclusive role in the diagnosis and follow-up of chromaffin tumors.~Nevertheless, in literature, few studies explore and reveal the utility of testing metanephrines for the evaluation of sympathetic activity and its associated cardiometabolic complications in patients with essential hypertension.