do they provide useful information about sympatho-adrenal function and catecholamine metabolism?
1. The clinical utility of plasma metadrenalines for examination of sympatho-adrenal function and catecholamine metabolism was assessed from plasma measurements of these metabolites in a number of clinical conditions (hypertension, cardiac failure, bilateral adrenalectomy and X-chromosomal deletions of the gene for monoamine oxidase), and before and during activation of sympathetic outflow or infusions of noradrenaline and adrenaline. 2. Plasma concentrations of normetadrenaline were less than 25% of those of noradrenaline, concentrations of metadrenaline and adrenaline were similar and those of sulphate-conjugated metadrenalines were 20- to 30-fold higher than free metadrenalines. Hypertensive patients had elevated plasma concentrations of adrenaline, noradrenaline and conjugated but not free metadrenalines. Cardiac failure patients had 2- to 4-fold increases in plasma noradrenaline and free and conjugated normetadrenaline. Adrenalectomy resulted in undetectable plasma concentrations
