Abstract
Plasma catecholamines were measured by employing a precise and sensitive double-isotope technique in 9 control subjects and in 20 patients with various types of hypertension. Venous blood was collected while the subjects rested in the supine position. In the control subjects total plasma catecholamine concentration averaged 0.25 ng/ml ± 0.08. The noradrenaline concentration was 0.21 ng/ml and the adrenaline concentration 0.05 ng/ml. Total plasma catecholamine concentration was normal in patients with renal and essential hypertension while the 4 patients with phaeocromocytoma showed values ranging from 0.48 to 7.90 ng/ml.