Endocrine Abstracts

Introduction: Biochemical testing for Paraganglioma/Pheochromocytoma (PGL/PHEO) is recommended in patients with classical symptoms, in those harbouring an adrenal incidentaloma and in patients who have a hereditary risk for developing a PGL/PHEO. Measurements of plasma free metanephrines and/or urinary fractionated metanephrines provide a highly sensitive test for diagnosis but false-positive results remain a problem.

Aim: Comparative analysis of plasma and urinary metanephrines results in a group of individuals suspected of having PGL/PHEO.

Subjects and methods: Retrospective analysis of tests performed at a tertiary hospital during the year 2015 (January 1st-December 31th) and correlation with imaging studies and clinical data.

Results: 686 measurements of urinary and/or plasma metanephrines, ordered by physicians of different medical specialties, were performed. From the analysis of these results, we identified 124 patients with both measurements; they were 77 women and 47 men with a mean age of 47.3 years (range 6–82). The main reason for testing was therapy-resistant or paroxismal hypertension (n=68; 54.8%) followed by the presence of an adrenal incidentaloma (n=13,10.4%). Abnormal high values were observed in 56 patients: in 44 (45.2%) only abnormal urine values, in 6 (4.8%) both urine and plasma abnormal values and in 6 (4.8%) only abnormal plasma values. 3/6 patients who presented elevation of urinary and plasma metanephrines had histologically proven disease (2 PHEO, 1 abdominal PGL). Among the patients with normal plasma metanephrines and high urinary metanephrines only one (2.3%) had a bilateral pheochromocytoma in the context of a MEN2A syndrome. None of the 6 patients with normal urinary metanephrines and increased plasma metanephrines had disease.

Conclusion: In the present series, all patients with a histologic diagnosis of PGL/PHEO had elevated urinary metanephrines regardless, in one case, normal plasma metanephrines. On the other hand, the frequency of increased urinary metanephrines without a positive imaging was very frequent.