title: Sensitive method for the quantification of urinary pyrimidine metabolites in healthy adults by gas chromatography-tandem mass spectrometry.
abstract: Enzyme deficiencies in pyrimidine metabolism are associated with a risk for severe toxicity against the antineoplastic agent 5-fluorouracil. To assess whether urinary levels of pyrimidines and their metabolites can be used for predicting patients' individual phenotype, a new gas chromatographic-tandem mass spectrometric method was developed which allows the simultaneous determination of uracil and thymine and their metabolites dihydrouracil, dihydrothymine, beta-ureidopropionic acid, beta-ureidoisobutyric acid, and the amino acids beta-alanine and beta-aminoisobutyric acid in human urine. Small aliquots (2-20 microl) of the urine samples were evaporated and derivatized to the tert.-butyldimethylsilyl derivatives before quantification, using the respective stable isotope-labelled analogues as internal standards. Analytical variation was acceptable with an intra-day imprecision (RSD) below 10%, for beta-ureidoisobutyric acid below 15%. The method was used for investigating the stability of urine samples and the influence of urine collection at different times.
authors.affiliation: Dr. Margarete Fischer-Bosch-Institute of Clinical Pharmacology, Auerbachstrasse 112, D-70376 Stuttgart, Germany. ute.hofmann@ikp-stuttgart.de
authors.forename: Ute
authors.initials: U
authors.lastname: Hofmann
authors.forename: Matthias
authors.initials: M
authors.lastname: Schwab
authors.forename: Sonja
authors.initials: S
authors.lastname: Seefried
authors.forename: Claudia
authors.initials: C
authors.lastname: Marx
authors.forename: Ulrich M
authors.initials: UM
authors.lastname: Zanger
authors.forename: Michel
authors.initials: M
authors.lastname: Eichelbaum
authors.forename: Thomas E
authors.initials: TE
authors.lastname: Mürdter
mesh_terms: D000328:Adult; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods*; D006801:Humans; D011743:Pyrimidines / Q000652:urine*; D012015:Reference Standards; D012016:Reference Values; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D011743:Pyrimidines