We discovered that CSF concentrations of pyruvate + oxaloacetic acid were significantly lower in the gliomas with IDH mutations compared with those with a wild-type IDH. In contrast, the CSF concentrations of lactic, citric, and isocitric acid were significantly higher in gliomas with IDH mutations compared with those of a wild-type IDH. In addition, the levels of the late TCA cycle metabolites that act downstream of isocitric acid decreased in the gliomas with IDH mutations. Here, IDH1 is linked to glioma.