24 h excretion patterns of free, conjugated and methylated catecholamines in man

A method based on high performance liquid chromatography with electrochemical detection is described for quantification of adrenaline, noradrenaline, dopamine (free and total), metanephrine, normetanephrine, and 3-methoxytyramine (free) in urine samples. Purification of the samples is achieved on disposable Bio-Rad ion-exchange columns in combination with small Sephadex G 10 columns. A clear circadian rhythm was found in the 24 h excretion pattern of free adrenaline and noradrenaline for 4 volunteers (city bus drivers during a working day). No rhythms were seen in the 24 h excretion pattern of free or conjugated dopamine, conjugated adrenaline or conjugated noradrenaline, or of the methylated free catecholamines. It is concluded that in order to obtain information about the neurotransmitter function of peripheral catecholamines it is sufficient to determine the non-conjugated compounds; values for the conjugated and methylated metabolites contribute no extra information.