Diagnostic meaning of blood p-cresol concentration in forensic autopsy cases.

In some forensic autopsy cases there are high concentrations of p-cresol in the blood. In vivo, p-cresol is the only isomer yielded by intestinal bacteria and is excreted into urine. We investigated the diagnostic meaning of p-cresol in the blood of forensic autopsy cases. Blood samples from 110 autopsy cases within 48 h of the postmortem interval (PMI) and 10 healthy adults were examined. Blood with p-cresol-d8 as an internal standard was analyzed using a GC-MS/MS method. Using acid and heat deproteinization, free (F) and conjugated (non-protein bound: C; protein bound: PC) p-cresol were individually analyzed. The p-cresol concentrations were 1.39 ± 0.86 µg/ml [mean ± SD] and 1.18 (0.19-18.80) µg/ml [median (range)] in healthy adults and autopsy cases, respectively. The p-cresol showed no significant relationship to age, sex, fasting duration, survival duration, or PMI. No significant differences were found between causes of death. Significantly higher levels of C p-cresol were found in cases with atherosclerosis in the basilar or renal arteries, or stenosis in the coronary artery. Significantly higher levels of p-cresol except F were found in cases with hyalinosis of the kidney. Cases with low BMI also showed significantly higher p-cresol concentrations. The 22 cases of abnormally high total p-cresol were investigated. It was considered that high concentrations of p-cresol could be an indicator of certain diseases and physical conditions that effect the production, absorption, metabolism, circulation, and excretion of p-cresol. Measuring the levels of p-cresol may provide valuable information about the antemortem physical conditions.