FREQUENCY OF PHEOCHROMOCYTOMA IN ADRENAL INCIDENTALOMAS AND UTILITY OF THE GLUCAGON TEST FOR THE DIAGNOSIS

To investigate the frequency of pheochromocytoma in patients with inci dentally discovered adrenal masses (incidentalomas) and to evaluate th e sensitivity, specificity and diagnostic accuracy of the Glucagon tes t in comparison with resting plasma catecholamines, 89 patients with a drenal incidentalomas (age range 23-80 yr; 41. males and 48 females) w ere studied, Fifty-seven patients were normotensive (SEP 130+/-1.8 mmH g; DBP 80+/-0.7 mmHg, mean+/-SE) and 32 had stable hypertension (SEP 1 55+/-3.3 mmHg, DBP 93+/-1.4 mmHg): no patient complained of typical si gns or symptoms of pheochromocytoma. Resting plasma samples for noradr enaline and adrenaline determination and, at appropriate intervals, th e Glucagon test (1 mg i.v.), were performed in all subjects. Diagnosis of pheochromocytoma was made on the basis of humoral evaluations and/ or surgical intervention in 6 patients (6.7%), of whom 3 hypertensives and 3 normotensives. Resting plasma catecholamines revealed 5 out of 6 patients with pheochromocytoma: in 3 cases both catecholamines were above the normal range, in 1 only adrenaline was elevated and in 1 cas e only noradrenaline. Similarity, the glucagon test identified 5/6 phe ochromocytomas: in 3 patients the response was abnormal for both catec holamines, in 1 only for adrenaline and in 1 case only for noradrenali ne. The sensitivity, specificity, and diagnostic accuracy of resting p lasma catecholamines and of the glucagon test were comparable: 83.3%, 96.3%, and 95.5%, respectively. In conclusion, the frequency of pheoch romocytoma in adrenal incidentalomas is not negligible, and since the diagnostic accuracy of the Glucagon test is the same of that of restin g plasma catecholamines, the former does not appear to offer additiona l advantages in the diagnosis of incidentally discovered pheochromocyt omas. (C) 1997, Editrice Kurtis.