GSTM1 and anemia (phenotype): In this study, we identified that a range of disrupted plasma metabolites correlated with Hb levels in patients with anemia of CRF, including those involved in aromatic amino acid metabolism, arginine and proline metabolism, branched-chain amino acid metabolism, ascorbate and aldarate metabolism, xenobiotic biodegradation and metabolism, the pentose phosphate pathway, steroid hormone biosynthesis, and glycerophospholipid metabolism (Fig. 5A).