Increased Urinary Excretion of 3-Methoxytyramine in Patients with Head and Neck Paragangliomas

Context: Patients with head-and-neck paragangliomas (HNPGL) are regularly screened for catecholamine excess. The clinical relevance of increased urinary secretion of 3-methoxytyramine is unclear in HNPGL. Objective: The aim of the study was to assess the prevalence and the clinical, biochemical, and radiological presentation of patients with HNPGL with increased urinary excretion of 3-methoxytyramine. Patients and Methods: A total of 136 consecutive patients with HNPGL were included and screened for catecholamine excess by measurement of 24-h urinary excretion of (nor) metanephrine, (nor) epinephrine, vanillylic mandelic acid, dopamine, and 3-methoxytyramine. In patients with catecholamine excess, abdominal/intrathoracic paragangliomas were excluded by (123)I-metaiodobenzyl-guanidine scintigraphy, magnetic resonance imaging, and/or computed tomography. Results: Urinary 3-methoxytyramine excretion was increased in 31 of the 136 patients (23%). In 18 of these 31 patients, this was the only sign of biochemical activity of HNPGL. Dopamine excretion was higher in subjects with increased 3-methoxytyramine excretion (1.62 +/- 0.1 mu mol/24 h vs. 2.5 +/- 0.3 mu mol/24 h; P <0.01). Of the 136 HNPGL patients, 21 (15%) had excessive excretion of at least one catecholamine and/or their metabolites when 3-methoxytyramine excretion was not taken into account. With the inclusion of patients with excessive 3-methoxytyramine excretion, 39 (29%) had excessive catecholamine excretion. Patients with 3-methoxytyramine excess had significantly more complaints of palpitations (P <0.01), diaphoresis (P = 0.03), collapse (P <0.05), and a higher pulse rate (P