Development of quantitative assay for simultaneous measurement of purine metabolites and creatinine in biobanked urine by liquid chromatography-tandem mass spectrometry

• Published in: Scandinavian Journal of Clinical and Laboratory Investigation
• Main Authors: Svistounov, Dmitri, Solbu, Marit Dahl, Jenssen, Trond Geir, Mathisen, Ulla Dorte, Hansen, Terkel, Elgstøen, Katja Benedikte Prestø, Zykova, Svetlana
• Format: Article in Journal/Newspaper
• Language: English
• Published: Taylor & Francis 2022
• Subjects: Liquid chromatography; allantoin; biological specimen bank; creatinine; hydrophilic interaction; hypoxanthine; mass spectroscopy; purines; reference ranges; solubility; uric acid; urine; xanthine; Arctic; Norway; Arctic University of Norway; UiT The Arctic University of Norway
• Online Access: https://hdl.handle.net/11250/3072859; https://doi.org/10.1080/00365513.2021.2015799

Purine metabolism is essential for all known living creatures, including humans in whom elevated serum concentration of purine break-down product uric acid (UA) is probably an independent risk factor for mortality, type 2 diabetes and cardiovascular events. An automated multiplex assay that measures several purine metabolites could therefore prove useful in many areas of medical, veterinary and biological research. The aim of the present work was to develop a sensitive LC-MS/MS method for simultaneous quantitation of xanthine, hypoxanthine, UA, allantoin, and creatinine in biobanked urine samples. This article describes details and performance of the new method studied in 55 samples of human urine. Archival sample preparation and effect of storage conditions on stability of the analytes are addressed. The intra-day and inter-day coefficients of variation were small for all the analytes, not exceeding 1% and 10%, respectively. Measurements of UA and creatinine in biobanked urine showed good agreement with values obtained using routine enzymatic assays on fresh urine. Spearman's correlation coefficients were 0.869 (p < .001) for creatinine and 0.964 (p < .001) for UA. Conclusion: the newly developed LC-MS/MS method allows reliable quantitative assessment of xanthine, hypoxanthine, allantoin, UA and creatinine. The proposed pre-analytical processing makes the method suitable for both fresh and biobanked urine stored frozen at -80 °C for at least 5.5 years. Keywords: Liquid chromatography; allantoin; biological specimen bank; creatinine; hydrophilic interaction; hypoxanthine; mass spectroscopy; purines; reference ranges; solubility; uric acid; urine; xanthine. The study has been funded by the following: 1. Helse Nord research foundation, 2017, project number: HNF1388-17. 2. Helse Nord research foundation, 2018, project number: HNF1430-18. 3. Familien Blix Fond, Project title: URIC ACID IN HEART AND KIDNEY DISEASE: development of new diagnostics and treatment. 4. UiT – The Arctic University of Norway and the ...