2037 Background: Mutation of IDH1 gene is a prognostic factor and a diagnostic hallmark of gliomas. Mutant IDH1 enzyme can convert α-KG into 2-Hydroxyglutarate(2HG); mutated gliomas have elevated amounts of intracellular 2HG. We analyzed 2HG concentration in plasma and urine in glioma patients(PTS) to identify a biomarker of IDH1 gene mutation Methods: All PTS had a prior histological confirmation of glioma, a recent brain MRI (within 2 weeks) showing the neoplastic lesions. The exclusion criteria were any chemotherapy performed within 28 days prior, other neoplastic and metabolic diseases. Plasma and urine samples were taken from all PTS and 2HG concentrations determined by liquid chromatography tandem mass spectrometry; Mann-Whitney test was used to test for differences in metabolite concentrations. ROC curve was used to evaluate the cut off value of 2HG biomarker. Results: 84 PTS were enrolled: 38 with IDH1 mutated and 46 IDH1 wild-type. Among PTS with mutant IDH1 we had 21 high-grade gliomas (HGG) and...