[Simultaneous determination of guanidinoacetate, creatine and creatinine by liquid chromatography-tandem mass spectrometry: a diagnostic tool for creatine deficiency syndromes in body fluids and a perspective use on cultured fibroblasts]. / Détermination simultanée du guanidinoacétate, de la créatine et de la créatinine par chromatographie liquide couplée à la spectrométrie de masse en tandem : outil de diagnostic biochimique pour les syndromes de déficit en créatine et perspectives d'utilisation sur les fibroblastes.

ABSTRACT

Guanidinoacetate (GAA) and creatine (Cr) are creatine deficiency syndromes (CDS) biochemical markers. We describe a liquid chromatography - tandem mass spectrometry method (LC/MSMS) performing simultaneous analysis of GAA, Cr and creatinine (Crn). Study of Cr uptake by fibroblasts for Cr transporter defect diagnosis is also assessed. The three butylated compounds were separated by liquid chromatography and MSMS quantification was achieved by isotopic dilution with electrospray positive ion mode. Linearity was demonstrated from 0 to 600, 675 and 4500 µmol/L and limit of quantification was 0.1, 0.04 and 0.9 µmol/L for GAA, Cr, and Crn respectively. Intra- and inter-assay precision for each analyte was better than 11%, and standard recoveries ranged from 83 to 109%. Reference values in cerebrospinal fluid samples for subjects ≥14 years were also established for GAA and Cr. Five fibroblast cell lines were used for Cr uptake study. Cr uptake by fibroblasts increased with the Cr media concentrations and was significantly inhibited by 3-guanidinopropionate (500 µmol/L), a Cr transporter inhibitor (96h incubation, [Cr media] = 25 µmol/L, p<0.05). A reliable LC/MSMS method for the diagnosis of CDS was developed in different biological fluids. Finally, results of the Cr uptake study reinforce the interest of this technique to diagnose Cr transporter deficiencies.