Plasma dopamine beta-hydroxylase in a noradrenalin-secreting pheochromocytoma.

Circulating dopamine beta-hydroxylase activity was studied in a case of a hypertensive patient bearing a pheochromocytoma. The tumour secreted noradrenalin. The enzyme activity was found to decrease gradually after removal of the tumour, and to reach a stable value, in correlation with the decrease of urinary catecholamines. It is concluded that some pheochromocytoma tumours are able to secrete dopamine beta-hydroxylase.