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?

Abstract

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.