Serum total p-cresol and indoxyl sulfate correlated with stage of chronic kidney disease in renal transplant recipients.

Uremic toxins are considered cardiovascular and mortality risk factors in chronic kidney disease (CKD) patients. Both p-cresol and indoxyl sulfate have been shown to induce oxidative stress in vitro and subsequent endothelial dysfunction in uremic patients. Our study evaluated the levels of p-cresol and indoxyl sulfate, and whether they contribute to the progression of CKD in transplant recipients. We retrospectively evaluated 95 patients who had received a transplant from February 1987 to June 2010 in our center; the recipients had a mean transplant duration of 5.3 ± 4.9 years and a mean age of 47.8 ± 14.1 years. Among them, 56.8% (54/95) were male. Patients with glomerular filtration rate (GFR) ≥ 60 mL/min/1.73 m(2) were selected for group 1 (n = 35), and those with GFR < 60 mL/min/1.73 m(2) were selected for group 2 (n = 60). Demographic and clinical data were compared between groups. Serum and urine levels of p-cresol and indoxyl sulfate were also obtained. Baseline serum p-cresol and indoxyl sulfate levels were significantly higher in advanced CKD stages (P = .001 and <.0001, respectively). Patients at advanced CKD stages (group 2) had lower serum levels of hemoglobin and albumin (P < .0001), but higher levels of total cholesterol, triglyceride, and uric acid levels (P = .04, .04 and .001, respectively). Body mass index, C-reactive protein, and serum calcium and phosphate levels showed no significant differences between groups. The cut-off value for serum p-cresol between groups was 1.28 umol/L (P = .01), and that for the indoxyl sulfate level was 0.98 umol/L (P = .0001). The serum p-cresol and indoxyl sulfate levels were significantly higher in advanced CKD stages in transplant recipients. To evaluate the use of serum p-cresol and indoxyl sulfate levels as a predictive tool for survival, larger clinical studies are needed.