Organ distribution of endogenous p-cresol in hemodialysis patients

Background : p-Cresol concentrations are high in the blood of hemodialysis (HD) patients. However, its organ distribution has not yet been investigated in detail. We herein report the distribution of p-cresol in HD patients from forensic autopsy cases. Methods : p-Cresol was measured in the blood, urine, lungs, liver, and kidneys from 4 HD and 4 non-HD cases. Samples were extracted with p-cresol-d8 (internal standard), derivatized, and injected on the GC-MS. Results and Discussion : The total urinary p-cresol/Cr was 79.73 ng/ml in HD cases, which was 16-fold higher than that in non-HD cases. p-Cresol in the blood and kidneys were 30-fold higher or more at 11.92 and 13.08 µg/mL(g), respectively. p-Cresol in the liver and lungs were approximately 20-fold higher at 4.82 and 9.99 µg/g, respectively. p-Cresol was markedly increased in not only the blood, but also the urine and organs of HD cases. The distribution of p-cresol in the blood, urine, and organs differed between HD and non-HD cases. In HD cases, the percentages of conjugated (C) and protein-bound conjugated (PC) urinary p-cresol were 57 and 41%, respectively. C and PC p-cresol was 66% and 25% in the kidneys, respectively, and similar results were obtained in the lungs.