BACKGROUND: Quantification of plasma free metanephrine (MN) and normetanephrine (NMN) is considered to be the most accurate test for the clinical chemical diagnosis of pheochromocytoma and follow-up of pheochromocytoma patients. Current methods involve laborious, time-consuming, offline sample preparation, coupled with relatively nonspecific detection. Our aim was to develop a rapid, sensitive, and highly selective automated method for plasma free MNs in the nanomole per liter range. METHODS: We used online solid-phase extraction coupled with HPLC-tandem mass spectrometric detection (XLC-MS/MS). Fifty microliters plasma equivalent was prepurified by automated online solid-phase extraction, using weak cation exchange cartridges. Chromatographic separation of the analytes and deuterated analogs was achieved by hydrophilic interaction chromatography. Mass spectrometric detection was performed in the multiple reaction monitoring mode using a quadrupole tandem mass spectrometer in positive electrospray ionization mode. RESULTS: Total run-time including sample cleanup was 8 min. Intra- and interassay analytical variation (CV) varied from 2.0% to 4.7% and 1.6% to 13.5%, respectively, whereas biological intra- and interday variation ranged from 9.4% to 45.0% and 8.4% to 23.2%. Linearity in the 0 to 20 nmol/L calibration range was excellent (R(2) > 0.99). For all compounds, recoveries ranged from 74.5% to 99.6%, and detection limits were <0.10 nmol/L. Reference intervals for 120 healthy adults were 0.07 to 0.33 nmol/L (MN), 0.23 to 1.07 nmol/L (NMN), and <0.17 nmol/L (3-methoxytyramine). CONCLUSIONS: This automated high-throughput XLC-MS/MS method for the measurement of plasma free MNs is precise and linear, with short analysis time and low variable costs. The method is attractive for routine diagnosis of pheochromocytoma because of its high analytical sensitivity, the analytical power of MS/MS, and the high diagnostic accuracy of free MNs.
BACKGROUND: Quantification of plasma free metanephrine (MN) and normetanephrine (NMN) is considered to be the most accurate test for the clinical chemical diagnosis of pheochromocytoma and follow-up of pheochromocytomapatients. Current methods involve laborious, time-consuming, offline sample preparation, coupled with relatively nonspecific detection. Our aim was to develop a rapid, sensitive, and highly selective automated method for plasma free MNs in the nanomole per liter range. METHODS: We used online solid-phase extraction coupled with HPLC-tandem mass spectrometric detection (XLC-MS/MS). Fifty microliters plasma equivalent was prepurified by automated online solid-phase extraction, using weak cation exchange cartridges. Chromatographic separation of the analytes and deuterated analogs was achieved by hydrophilic interaction chromatography. Mass spectrometric detection was performed in the multiple reaction monitoring mode using a quadrupole tandem mass spectrometer in positive electrospray ionization mode. RESULTS: Total run-time including sample cleanup was 8 min. Intra- and interassay analytical variation (CV) varied from 2.0% to 4.7% and 1.6% to 13.5%, respectively, whereas biological intra- and interday variation ranged from 9.4% to 45.0% and 8.4% to 23.2%. Linearity in the 0 to 20 nmol/L calibration range was excellent (R(2) > 0.99). For all compounds, recoveries ranged from 74.5% to 99.6%, and detection limits were <0.10 nmol/L. Reference intervals for 120 healthy adults were 0.07 to 0.33 nmol/L (MN), 0.23 to 1.07 nmol/L (NMN), and <0.17 nmol/L (3-methoxytyramine). CONCLUSIONS: This automated high-throughput XLC-MS/MS method for the measurement of plasma free MNs is precise and linear, with short analysis time and low variable costs. The method is attractive for routine diagnosis of pheochromocytoma because of its high analytical sensitivity, the analytical power of MS/MS, and the high diagnostic accuracy of free MNs.
Authors: Thamara E Osinga; Anouk N A van der Horst-Schrivers; Martijn van Faassen; Michiel N Kerstens; Robin P F Dullaart; Karel Pacak; Thera P Links; Ido P Kema Journal: Clin Biochem Date: 2016-02-10 Impact factor: 3.281
Authors: Martine F Luxwolda; Remko S Kuipers; Ido P Kema; E van der Veer; D A Janneke Dijck-Brouwer; Frits A J Muskiet Journal: Eur J Nutr Date: 2012-08-10 Impact factor: 5.614
Authors: Graeme Eisenhofer; Peter Lattke; Maria Herberg; Gabriele Siegert; Nan Qin; Roland Därr; Jana Hoyer; Arno Villringer; Aleksander Prejbisz; Andrzej Januszewicz; Alan Remaley; Victoria Martucci; Karel Pacak; H Alec Ross; Fred C G J Sweep; Jacques W M Lenders Journal: Ann Clin Biochem Date: 2012-10-12 Impact factor: 2.057
Authors: Wilhelmina H A de Jong; Marianne H L I Wilkens; Elisabeth G E de Vries; Ido P Kema Journal: Anal Bioanal Chem Date: 2010-02-07 Impact factor: 4.142
Authors: Maarten P van den Berg; Rowida Almomani; Italo Biaggioni; Martijn van Faassen; Pim van der Harst; Herman H W Silljé; Irene Mateo Leach; Marc H Hemmelder; Gerjan Navis; Gert Jan Luijckx; Arjan P M de Brouwer; Hanka Venselaar; Marcel M Verbeek; Paul A van der Zwaag; Jan D H Jongbloed; J Peter van Tintelen; Ron A Wevers; Ido P Kema Journal: Circ Res Date: 2018-01-17 Impact factor: 17.367