Introduction

The discovery that vanilmandelic acid (VMA) is the main metabolite of adrenaline (A) and noradrenaline (NA) ( 7 ) led soon to the clarification of the major pathways of metabolism of these hormones (page 11) . The methods for the urinary determination of the major metabolites of and N A were available shortly thereafter also for use in clinical diagnosis. The determination of A and N A excretions in the urine is still, however, the most reliable criterion of the activities of the sympathetic nervous system and the adrenal glands (68). ' The usefulness of excretion studies for this purpose is well supported also by the investigations of Pekkarinen and his working group (37, 1 1 1 , 138, 194, 196, 198, 207, 222). The possibility of determining the metabolites of A and N A has, however, opened new opportunities for the study of both the physiological significance of these hormones and their normal and pathological secretion and metabolism. Examination of these metabolites in the urine is usually more practical owing to their stability and great quantities. This is true of VMA, which is excreted in the urine in about 70 times as large amounts as A and N A together (292).