Urinary 5-hydroxytryptophol following acute ethanol consumption: Clinical evaluation and potential aviation applications

Hypothesis: The unknown prevalence of alcohol use and misuse among aviation pilots, crewmembers and associated support personnel call for continuous improvement of methods for detecting recent alcohol use. Early detection is essential to proper treatment and prevention of potentially catastrophic mishaps. Urinary 5-hydroxytryptophol (5HTOL), a serotonin (5HT) metabolite, has shown promise in the clinical setting as a noninvasive marker of recent alcohol consumption. Methods: The urinary 5HTOL concentrations of 11 male and female subjects were followed for approximately 24 h following dosing with ethanol 0.6 g . kg(-1). Concentrations were reported as a ratio of 5HTOL to 5-hydroxy-indoleacetic acid (5HIAA), 5HTOL/5HIAA (pmol/nmol), to compensate for urinary dilution and elevated 5HTOL levels due to dietary intake. Data from one male subject was excluded after he admitted to continued alcohol consumption subsequent to dosing and missing several urine samples. Results: 5HTOL/5HIAA ratios remained above the 15 pmol/nmol cutoff for recent alcohol use for approximately 11-16 h in all except one subject. Calculations based on body weight and administered alcohol dose suggest that measurable blood alcohol levels would exist for only 5-7 h post ingestion. Conclusion: This study confirmed the extended elevation of 5HTOL/5HIAA ratios observed in earlier studies, even at the relatively low alcohol dose used herein. 5HTOL appears to be a marker for acute alcohol consumption worthy of further investigation by military and civilian aviation authorities. Potential aviation applications of 5HTOL include validation of measurable blood alcohol concentrations, investigation of poor performance due to hangover effects, and as a forensic toxicology tool in aircraft accident investigations to distinguish between actual alcohol ingestion and post-mortem alcohol synthesis.