[Bilateral adrenal pheochromocytoma. Diagnosis and follow-up using the clonidine test and measurement of plasma neuropeptide Y concentration].

The role of the clonidine suppression test and determination of the plasma concentration of noradrenaline and of neuropeptide Y (NPY) for the diagnosis and monitoring of bilateral pheochromocytoma was studied in a ten year old girl. Prior to tumor removal plasma concentration of noradrenaline (25.9 nmol/l) and NPY (14 pmol/l) were markedly elevated. Inhibition of central sympathetic activity by clonidine (150 micrograms orally) did not lower the plasma concentration of noradrenaline (70.4 nmol/l) and NPY (52.6 pmol/l). However in an adolescent boy with renal hypertension plasma concentration of noradrenaline and NPY fell following clonidine application (noradrenaline from 1.9 to 1.3 nmol/l, NPY from 3.6 to 2.4 pmol/l). After complete removal of the pheochromocytoma noradrenaline and NPY fell back to normal.