Andraz Smon1, Vanja Cuk2, Jernej Brecelj2, Simona Murko3, Urh Groselj2, Mojca Zerjav Tansek2, Tadej Battelino4, Barbka Repic Lampret2. 1. University Medical Centre Ljubljana, University Children's Hospital, Bohoriceva 20, Ljubljana, Slovenia. Electronic address: andraz.smon@kclj.si. 2. University Medical Centre Ljubljana, University Children's Hospital, Bohoriceva 20, Ljubljana, Slovenia. 3. University Medical Center Hamburg-Eppendorf, Newborn Screening and Metabolic Diagnostics Unit, Martinistrasse 52, Hamburg, Germany. 4. University Medical Centre Ljubljana, University Children's Hospital, Bohoriceva 20, Ljubljana, Slovenia; University of Ljubljana, Faculty of Medicine, Korytkova ulica 2, Ljubljana, Slovenia.
Abstract
OBJECTIVES: Precise quantification of amino acids (AAs) is mandatory for successful diagnosis and monitoring of patients with metabolic diseases. We compared ion-exchange chromatography (IEC) and liquid chromatography with tandem mass spectrometry (LC-MS/MS), the two methods most commonly used in clinical laboratories for the quantification of AAs in physiological samples. DESIGN & METHODS: 123 apparently healthy children were selected for the study. The plasma samples for LC-MS/MS were prepared accordingly to the aTRAQ Kit for Physiological Fluids on Sciex 3200 Qtrap, for IEC according to the protocol from Pickering laboratories on the AA analyzer Pinnacle PCX. Results were interpreted using the Pearson correlation coefficient and the percent difference Bland-Altman test. RESULTS: The Spearman correlation coefficients of the 14 AAs that we evaluated varied from 0.67 in Tau to 0.89 in Leu and Thr. The mean differences in measurements (IEC compared to LC-MS/MS) of 11 AAs complied with our acceptance criterion of <15%, the differences of Ser and Tyr were higher (19.5% and -19.0%, respectively), and the measured concentrations of Cit were much lower in LC-MS/MS than IEC (31% difference). CONCLUSION: The two methods are sufficiently comparable for most AAs and the reference values for individual AAs did not have to be refined, with the exception of citrulline. For the monitoring of patients on therapy (e.g. patients with phenylketonuria), it is still advisable to always use the same analytical method for the quantification of AAs.
OBJECTIVES: Precise quantification of amino acids (AAs) is mandatory for successful diagnosis and monitoring of patients with metabolic diseases. We compared ion-exchange chromatography (IEC) and liquid chromatography with tandem mass spectrometry (LC-MS/MS), the two methods most commonly used in clinical laboratories for the quantification of AAs in physiological samples. DESIGN & METHODS: 123 apparently healthy children were selected for the study. The plasma samples for LC-MS/MS were prepared accordingly to the aTRAQ Kit for Physiological Fluids on Sciex 3200 Qtrap, for IEC according to the protocol from Pickering laboratories on the AA analyzer Pinnacle PCX. Results were interpreted using the Pearson correlation coefficient and the percent difference Bland-Altman test. RESULTS: The Spearman correlation coefficients of the 14 AAs that we evaluated varied from 0.67 in Tau to 0.89 in Leu and Thr. The mean differences in measurements (IEC compared to LC-MS/MS) of 11 AAs complied with our acceptance criterion of <15%, the differences of Ser and Tyr were higher (19.5% and -19.0%, respectively), and the measured concentrations of Cit were much lower in LC-MS/MS than IEC (31% difference). CONCLUSION: The two methods are sufficiently comparable for most AAs and the reference values for individual AAs did not have to be refined, with the exception of citrulline. For the monitoring of patients on therapy (e.g. patients with phenylketonuria), it is still advisable to always use the same analytical method for the quantification of AAs.
Authors: N Deianova; S El Manouni El Hassani; E A Struijs; E E W Jansen; A Bakkali; M A van de Wiel; W P de Boode; C V Hulzebos; A H van Kaam; B W Kramer; E d'Haens; D C Vijlbrief; M M van Weissenbruch; W J de Jonge; M A Benninga; H J Niemarkt; N K H de Boer; T G J de Meij Journal: Sci Rep Date: 2022-07-19 Impact factor: 4.996