DISTINGUISHING INGESTED ETHANOL FROM MICROBIAL FORMATION BY ANALYSIS OF URINARY 5-HYDROXYTRYPTOPHOL AND 5-HYDROXYINDOLEACETIC ACID

During the metabolism of ethanol, the metabolic conversion of serotoni n (5-hydroxytryptamine) is altered, and, as a consequence, the ratio o f 5-hydroxytryptophol (5HTOL) to 5-hydroxyindole-3-acetic acid (5HIAA) excreted in urine increases appreciably. The ratio of metabolites rem ains elevated for several hours after ethanol is no longer detectable. In the present study, urine specimens were supplemented with glucose and Candida albicans, a common human pathogenic yeast, and the formati on of ethanol and the changes in the 5HTOL/5HIAA ratio were examined d uring one week of storage. Despite the production of high concentratio ns of ethanol (peak level 171 mmol/L, or 788 mg/dL), the 5HTOL/5HIAA r atio remained constant. The urinary 5HTOL/5HIAA ratio was also compare d with urinary and blood ethanol levels in specimens selected at rando m during forensic autopsies. Elevated 5HTOL/5HIAA ratios were found in all specimens with detectable urinary ethanol. Some specimens showed elevated ratios of serotonin metabolites even though no ethanol was de tected, indicating that these subjects had consumed ethanol prior to d eath but that the concentration had already returned to zero or was be low the detection limit. In one case, postmortem ethanol formation was suspected, because blood ethanol concentration was 16.8 mmol/L (77 mg /dL) whereas urinary ethanol was zero. The urinary 5HTOL/5HIAA ratio f ell within normal limits, which confirmed the suspicion of postmortem ethanol synthesis in the blood specimen. The present results indicate that the 5HTOL/5HIAA ratio in urine provides a useful method to distin guish between ethanol that might have been synthesized postmortem, or generated in vitro, from ethanol excreted in urine as a result of drin king.