GSTM1 and chronic kidney disease: The other correlations related to log-IS included positive correlations with log-transformed blood urea nitrogen (log-BUN, p < 0.001) and log-creatinine (p < 0.001), which are solutes related to renal dysfunction, and a negative correlation with albumin (p = 0.004) and Hb (p = 0.003), suggesting their role in CKD-related metabolic and vascular disturbances.