Increased urinary excretion of 3-methoxytyramine in patients with head and neck paragangliomas.

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. 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. 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-metaiodobenzylguanidine scintigraphy, magnetic resonance imaging, and/or computed tomography. 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 micromol/24 h vs. 2.5 +/- 0.3 micromol/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 < 0.01). Increased excretion of 3-methoxytyramine was not associated with particular types of HNPGL or genotypes. A substantial number of HNPGL patients have biochemically active tumors, reflected in increased excretion of 3-methoxytyramine, associated with increased dopamine excretion. Some patients only display increased excretion of 3-methoxytyramine, but not of other catecholamines or their metabolites.