Rapid screening of high-risk patients for disorders of purine and pyrimidine metabolism using HPLC-electrospray tandem mass spectrometry of liquid urine or urine-soaked filter paper strips.
BACKGROUND
A rapid and specific screening method for patients at risk of inherited disorders of purine and pyrimidine metabolism is desirable because symptoms are varied and nonspecific. The aim of this study was to develop a rapid and specific method for screening with use of liquid urine samples or urine-soaked filter paper strips.


METHODS
Reverse-phase HPLC was combined with electrospray ionization (ESI), tandem mass spectrometry (MS/MS), and detection performed by multiple reaction monitoring. Transitions and instrument settings were established for 17 purines or pyrimidines. Stable-isotope-labeled reference compounds were used as internal standards when available.


RESULTS
Total analysis time of this method was 15 min, approximately one-third that of conventional HPLC with ultraviolet detection. Recoveries were 96-107% in urine with added analyte, with two exceptions (hypoxanthine, 64%; xanthine, 79%), and 89-110% in urine-soaked filter paper strips, with three exceptions (hypoxanthine, 65%; xanthine, 77%; 5-hydroxymethyluracil, 80%). The expected abnormalities were easily found in samples from patients with purine nucleoside phosphorylase deficiency, ornithine transcarbamylase deficiency, molybdenum cofactor deficiency, adenylosuccinase deficiency, or dihydropyrimidine dehydrogenase deficiency.


CONCLUSIONS
HPLC-ESI MS/MS of urine allows rapid screening for disorders of purine and pyrimidine metabolism. The filter paper strips offer the advantage of easy collection, transport, and storage of the urine samples.
Ito
T
T
Academic Medical Center, University of Amsterdam, Emma Children's Hospital and Department of Clinical Chemistry, P.O. Box 22700, 1100 DE Amsterdam, The Netherlands.
van Kuilenburg
A B
AB
Bootsma
A H
AH
Haasnoot
A J
AJ
van Cruchten
A
A
Wada
Y
Y
van Gennip
A H
AH
D002851:Chromatography, High Pressure Liquid; D006801:Humans; D013058:Mass Spectrometry; D010209:Paper; D011684:Purine Nucleosides / Q000378:metabolism / Q000652:urine; D011686:Purine-Pyrimidine Metabolism, Inborn Errors / Q000652:urine*; D011741:Pyrimidine Nucleosides / Q000378:metabolism / Q000652:urine; D015203:Reproducibility of Results; D013048:Specimen Handling
D011684:Purine Nucleosides; D011741:Pyrimidine Nucleosides