A mass spectrometric method for quantification of tryptophan-derived uremic solutes in human serum

Abstract

In addition to various physiologic roles, emerging evidence strongly points to pathogenic roles of tryptophan and of its metabolites, especially in diseases such as renal failure. Accurate estimation of levels of these metabolites in blood is important to mechanistically probe their contribution to disease pathogenesis, while clinically, such a panel can be used to risk stratify patients for a clinical phenotype. Herein, we describe a comprehensive liquid chromatography-mass spectrometry (LC/MS)-based method to determine the level of tryptophan and its metabolites (kynurenine, kynurenic acid, xanthurenic acid, anthranilic acid, indoxyl sulfate and indoxyl acetate). Human sera samples were processed through a C18 column followed by application of a binary gradient and quantitation by MS/MS. The linearity, lower limit of detection, inter- and intraassay variabilities and recovery were determined, yielding a precise, reproducible method for all the metabolites. Unlike previous studies, we further validated these methods in a well-characterized set of human sera from end stage renal disease patients compared to age-, gender- and ethnic-background matched human controls. Overall, we report an optimized LC/MS-based estimation of a comprehensive panel of tryptophan-derived metabolites with quality features within FDA standards, underscoring their readiness for translational use.

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“…The Metabolomics Service Center at the Chemical Instrumentation Center, Boston University, analyzed the samples for Kyn and IS levels, as we have previously described. 32…”

Targeting STUB1–tissue factor axis normalizes hyperthrombotic uremic phenotype without increasing bleeding risk

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Measurement of Plasma Tryptophan Metabolites: Clinical and Experimental Application for Depression and Stress States Assessment

“…There are several researches for the simultaneous analyses of TRP metabolites using LC-MS or LC-MS/MS methods for clinical samples such as human serum and plasma [5,6]. In general, isotope-labeled internal standards are used in LC-MS/MS analysis to improve the accuracy, although isotope-labeled regents are expensive and limited availability [7,8]. Even though less accurate, acceptable results can be obtained without internal standards for the screening purposes.…”