Analysis of plasma 3-methoxytyramine, normetanephrine and metanephrine by ultraperformance liquid chromatographytandem mass spectrometry: utility for diagnosis of dopamine-producing metastatic phaeochromocytoma

Abstract

Background: Measurements of plasma normetanephrine (NMN) and metanephrine (MN) provide a sensitive test for diagnosis of phaeochromocytomas and paragangliomas (PPGLs), but do not allow detection of dopamine-producing tumours. Here we introduce a novel mass spectrometric based method coupled to ultraperformance liquid chromatography (LC-MS/MS) for measuring NMN, MN and 3-methoxytyramine (MTY), the O-methylated metabolite of dopamine. Methods: Specific collision-induced fragment ions assessed by multireaction monitoring transitions were used for identification, with quantification according to signal intensities of analytes relative to stable isotope labelled internal standards. Results for solid-phase extracted samples from 196 subjects analysed by LC-MS/MS were compared with those analysed by liquid chromatography with electrochemical detection (LC-ECD). Concentration ranges in 125 volunteers were compared with those from 63 patients with PPGLs, including 14 with metastatic disease. Results: The LC-MS/MS method showed linearity over four orders of magnitude with analytical sensitivity sufficient to measure to 0.02 nmol/L. Intra-and inter-assay coefficients of variation ranged from 2.8% to 13.5%. NMN and MN were respectively measured 17% and 10% higher and MTY 26% lower by LC-MS/MS than by LC-ECD. Medians and ranges for 3-methoxytramine, NMN and MN were respectively 0.08 (0.03 -0.13), 0.35 (0.13 -0.95) and 0.15 (0.07 -0.33) nmol/L in volunteers. Among patients with PPGLs, plasma methoxytyramine was six-fold higher in patients with than without metastastases (1.09 versus 0.19 nmol/L) and in three patients was the only metabolite increased. Conclusions: The LC-MS/MS method enables accurate, selective and sensitive measurements of catecholamine O-methylated metabolites that should be particularly useful for screening and management of dopamine-producing metastatic PPGLs.

Interference from 3-O-Methyldopa with Ultra–High Performance LC-MS/MS Measurements of Plasma Metanephrines: Chromatographic Separation Remains Important

“…Phospholipids are a main constituent of exhaled breath particles originating from the surfactant (3 ). The findings of this study extended this knowledge by demonstrating that abnormal phospholipids formed in blood following heavy alcohol consumption (i.e., PEth) (2 ) are also measurable in breath.…”

“…The exact relationship between alcohol consumption and PEth in breath, and the association between concentrations in breath and blood, remains to be elucidated. 3 ), for which the conventional product ion produced by collision-induced fragmentation of the precursor ion [MϩH ϩ ] is further fragmented in an ion trap to produce a "second generation product ion." This approach can eliminate occasional interferences during measurements of metanephrines from unknown substances in plasma samples.…”

“…This approach can eliminate occasional interferences during measurements of metanephrines from unknown substances in plasma samples. We outline here interference from an endogenous analyte present in all plasma samples, 3-Omethyldopa, which cannot be eliminated by MRM 3 . The interference affects measurements of methoxytyramine, the O-methylated metabolite of dopamine, important for diagnosis of chromaffin cell tumors and identification of metastatic disease (2,3 ).…”

Seasonal variation in plasma free normetanephrine concentrations: implications for biochemical diagnosis of pheochromocytoma

“…Respective inter-assay coefficients of variation for normetanephrine and metanephrine averaged 4.9 and 5.2% at Dresden and 4.6 and 7.0% at Nijmegen. In studies involving forearm warming, all measurements of plasma normetanephrine and metanephrine concentrations were performed using liquid chromatography with tandem mass spectrometry (23).…”

Plasma Metanephrine for Assessing the Selectivity of Adrenal Venous Sampling

“…At the University Hospital Düsseldorf, cortisol measurements were performed by an Elecsys analyzer (Roche Diagnostics, Mannheim, Germany). Plasma concentrations of metanephrines and catecholamines were measured at a single central laboratory (Hospital Carl Gustav Carus, Dresden) using liquid chromatography with tandem mass spectrometry 11 or electrochemical detection.…”