Higher Creatinine Concentrations in Ethyl Glucuronide-Positive Urine Specimens Collected from Subjects in a Controlled Alcohol Abstinence Program: Is Serum Creatinine a Good Marker of Renal Function in Drinkers?

Aims The aim of this study was to examine urine creatinine concentrations in drivers submitted to controlled alcohol abstinence programs. Methods Urine samples (n = 32,210) were screened for ethyl glucuronide (EtG) by immunoassay during a 2-year period. Non-negatives underwent EtG and ethyl sulfate (EtS) confirmation by coupled-column Liquid Chromatography-Tandem Mass Spectrometry. Urine samples were tested for dilution by the analysis of creatinine content with <0.2 g/l indicating a dilute specimen. Results The mean urine creatinine was significantly higher in EtG positives compared to negatives (1.47 ± 0.98 vs. 1.17 ± 0.79 g/l). The difference between positives and negatives was consistent within genders and age groups (<45; ≥45). The higher urinary creatinine in EtG positives is explained by a late antidiuretic effect of alcohol. Conclusion Attempts to dilute urine specimens by drinking water or other liquids before voiding are less effective for EtG/EtS compared with illicit drugs excreted in urine. If the temporary decrease in serum creatinine as a consequence of the late antidiuretic effect of alcohol is confirmed by controlled studies, serum creatinine as an indicator of kidney function should be reconsidered in drinkers. [ABSTRACT FROM AUTHOR]