Endocrine Abstracts

Introduction: Paragangliomas/pheochromocytomas present frequently with vague symptomatology which makes its diagnosis difficult and challenging. Cuantification of fractionated metanephrines and fractionated catecholamines in 24 h urine sample are used for diagnosis. There are situationes that can produce false positive results such as stress, drugs or smoking that must be taken into account.

Patients and methods: Retrospective study on the requests made for the diagnosis of pheochromocytoma/paraganglioma to the laboratory with the determinations of fractionated catecholamines and metanephrines during 10 months. Determinations were analysed by HPLC with electrochemical detector (Teknochroma^®).

Results: During this period 260 determinatios (of 218 patients) were analysed. 10 of these patients were diagnosed of pheochromocytoma, nine of extraadrenal paraganglioma and 199 patients did not present either of the pathologies. Patients with paraganglioma were excluded (Table 1).

Of the patients who did not present pheochromocytoma (199), 35 had elevated catecholamines and/or fractionated metanephrines (18% false positive), 17 were due to antihypertensive or antidepressant drugs, 11 had other adrenal pathologies and seven others.

Conclusions: 1. Urinary fractionated metanephrines have a higher specificity than catecholamines. Both of them present the same sensitivity in our patients.

2. The rate of false positive results surpasses those of true positive, especially those produced by drugs, as published in literature.