Assessment of Plasma Oxalate Concentration in Patients With CKD

Pfau A, Wytopil M, Chauhan K, Reichel M, Coca SG, Aronson PS, Eckardt KU, Knauf F (2020)

Publication Type: Journal article

Publication year: 2020

Journal

Kidney International Reports Elsevier

Book Volume: 5

Pages Range: 2013-2020

Journal Issue: 11

DOI: 10.1016/j.ekir.2020.08.029

Abstract

Introduction: Alterations in oxalate homeostasis are associated with kidney stone disease and progression of chronic kidney disease (CKD). However, accurate measurement of plasma oxalate (POx) concentrations in large patient cohorts is challenging as prompt acidification of samples has been deemed necessary. In the present study, we investigated the effects of variations in sample handling on POx results and examined an alternative strategy to the established preanalytical procedures. Methods: The effect of storage time at room temperature (RT) and maintenance of samples at −80°C was tested. POx was measured in 1826 patients enrolled in the German Chronic Kidney Disease (GCKD) study, an ongoing multicenter, prospective, observational cohort study. Results: We demonstrate that POx concentrations increased rapidly when samples were maintained at RT. This was most relevant for POx <10 μM, as concentrations more than doubled within a few hours. Immediate freezing on dry ice and storage at −80°C provided stable results and allowed postponement of acidification for >1 year. In the patients of the lowest estimated glomerular filtration rate (eGFR) quartile, median POx was 2.7 μM (interquartile range [IQR] <2.0–4.2) with a median eGFR of 25.1 ml/min per 1.73 m2 (IQR 20.3–28.1). Conclusion: We conclude that immediate freezing and maintenance of plasma samples at -80°C facilitates the sample collection process and allows accurate POx assessment in large cohorts. The present study may serve as a reference for sample handling to assess POx in clinical trials and to determine its role in CKD progression.

Authors with CRIS profile

Kai-Uwe Eckardt Department of Medicine 4 – Nephrology and Hypertension

Involved external institutions

Icahn School of Medicine at Mount Sinai US United States (USA) (US) Charité - Universitätsmedizin Berlin DE Germany (DE) Yale School of Medicine US United States (USA) (US)

How to cite

APA:

Pfau, A., Wytopil, M., Chauhan, K., Reichel, M., Coca, S.G., Aronson, P.S.,... Knauf, F. (2020). Assessment of Plasma Oxalate Concentration in Patients With CKD. Kidney International Reports, 5(11), 2013-2020. https://doi.org/10.1016/j.ekir.2020.08.029

MLA:

Pfau, Anja, et al. "Assessment of Plasma Oxalate Concentration in Patients With CKD." Kidney International Reports 5.11 (2020): 2013-2020.

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