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Barco S.,Uo Laboratorio Centrale Of Analisi | Alpigiani M.G.,Clinica Pediatrica | Ghiggeri G.M.,U.O. Nefrologia e Dialisi | Talio M.,Uo Laboratorio Centrale Of Analisi | And 3 more authors.
Clinical Biochemistry | Year: 2014

Objective: Measurement of urinary fractionated metanephrines represents a first-line test for the biochemical diagnosis of pheochromocytoma. The high performance liquid chromatography coupled to electrochemical detection (HPLC-EC) assays used in the routine clinical laboratory can be subjected to analytical interferences by the presence of drugs or their metabolites. In this paper we describe the interference on urinary normetanephrine (uNMN) caused by amoxicillin. Design and methods: Two pediatric patients suspected of pheochromocytoma had very high uNMN levels (2543 and 4227. μg/g Cr respectively; upper reference value: 339. μg/g Cr). Amoxicillin interference was assessed by comparison for co-elution with uNMN and by LC-MS/MS analysis. Results: After amoxicillin interference was suspected and the therapy was stopped uNMN levels returned to normal (149 and 214. μg/g Cr respectively). Chromatograms obtained by HPLC-EC clearly showed that amoxicillin co-elutes with uNMN. Patients' uNMN levels measured by LC-MS/MS were in the normal range. Conclusion: Amoxicillin is responsible for analytical interference on HPLC-EC assay for uNMN. This finding can be of help in distinguishing true-positive from false-positive results in the course of a biochemical diagnosis for pheochromocytoma. © 2014 The Canadian Society of Clinical Chemists. Source

Cangemi G.,Uo Laboratorio Centrale Of Analisi | Barco S.,Uo Laboratorio Centrale Of Analisi | Barbagallo L.,Uo Laboratorio Centrale Of Analisi | Di Rocco M.,UO Pediatria II | And 5 more authors.
Scandinavian Journal of Clinical and Laboratory Investigation | Year: 2012

Background. Classical galactosemia is a rare but very severe disease characterized by a deficiency of the galactose-1-phosphate uridyltransferase enzyme. The confirmed galactosemic patients are treated with a galactose-restricted diet. Nevertheless, metabolites such as galactose-1-phosphate can accumulate in red blood cells of treated patients and its measurement is a standard practice for their monitoring. At present, no commercial methods for measuring galactose-1-phosphate in erythrocytes are available. Methods. In this study, we will describe the optimization and laboratory validation of a previously published quantitative gas chromatographic-mass spectrometric method and its clinical validation on normal donors and galactosemic patients both at the diagnosis and during the follow-up. Results. The method was technically optimized and validated for its clinical use on normal donors and galactosemic newborns, children and adults. The method was suitable for the monitoring of dietary compliance. Galactose-1-phosphate levels were found to be well correlated with the clinical signs in the galactosemic patients at the follow-up. Conclusions. This paper provides information on the measurement of Galactose-1-phosphate levels that can be very useful for the management of classical galactosemia. © 2012 Informa Healthcare. Source

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