Combining markers of nephrotoxicity and hepatotoxicity for improved monitoring and detection of chronic alcohol abuse

Background: Most of the commonly used markers of chronic alcohol abuse reflect alcohol hepatotoxicity; however, such abuse is deleterious to the kidneys as well. Combined use of serum markers of liver origin and urinary markers of kidney origin may be of diagnostic advantage. Methods: The study was performed in 73 male alcoholics undergoing detoxification and 36 male alcoholics who had maintained abstinence for ≥6 weeks. Factor analysis, discriminant analysis and receiver operating characteristic (ROC) analysis were used to assess the discriminative power of two urinary markers of alcohol nephrotoxicity, namely β-N-acetylhexosaminidase (Hex, EC 3.2.1.52) and alanine aminopeptidase (EC 3.4.11.2), and of three serum markers of alcohol hepatotoxicity, namely aspartate aminotransferase (EC 2.6.1.1), alanine aminotransferase (EC 2.6.1.2) and γ-glutamyltransferase (GGT, EC 2.3.2.2), and of their quantitative combinations. Results: The discriminative power of the urinary markers matched that of the serum markers. Hex and GGT appeared to be the best for discriminating the study groups. Their combination given by the equation G&H=0.62×ln(GGT)+0.72×ln(Hex) showed excellent discriminative ability (ROC area under the curve 0.92) that was significantly higher than that of any single marker in this report, indicating superior diagnostic accuracy of the compound marker. Conclusions: Kidney-derived urinary markers, particularly Hex, can complement or replace, if necessary, serum markers of chronic alcohol abuse that relate to alcohol hepatotoxicity. The compound marker proposed seems a promising tool for the monitoring and perhaps detection of chronic alcohol abuse and warrants further studies. Clin Chem Lab Med 2006;44:1446–52.