GSTM1 and kidney failure: Toxicity of free heme has been mainly attributed to its pro-oxidative nature, which may either directly damage cells or may promote generation of toxic lipid-oxidation products.22, 23, 24, 25, 26, 27 Several pathways of renal tubule cell death may be relevant to AKI and renal failure following sustained exposures to Hb and its components (globin, heme, and iron).