Low specificity of urinary 3-methoxytyramine in screening of dopamine-secreting pheochromocytomas and paragangliomas

Among the urinary compounds measured in screening for pheochromocytomas and paragangliomas (PPGL), 3-methoxytyramine (3-MT) has a controversial place. In this study, we therefore aimed to assess the diagnostic value of an isolated elevated urinary 3-MT concentration. We collected clinical data from patients with an isolated elevated level of 3-MT/creatinine (3-MT/Cr) and from control subjects, without elevated 3-MT/Cr levels. Among 64 patients with an isolated elevation of 3-MT/Cr and 66 controls, 7 patients had PPGL compared to 8 controls. There was no difference in 3-MT/Cr values between the different types of tumor diagnosed. This study suggests that an elevated urinary 3-MT/Cr level is not specifically associated with dopamine-secreting PPGL. and may therefore have little value in PPGL screening.