[Concentration of cotinine and trans-3'-hydroxycotinine and its glucuronides in urine of smoking pregnant women]

Abstract

To assess the exposure to tobacco smoke constituents, the biomarkers are used. In most studies conducted among active smokers, the cotinine is usually utilised as such a biomarker. The aim of this study was to estimate an application of determining two nicotine metabolites, cotinine and trans-3'-hydroxycotinine (3-HC) in order to assess cigarette smoking among pregnant women. There were 25 patients (15 smokers, 10 non-smokers) admitted to Delivery Ward in Gynecology and Obstetrics Clinical Hospital of the University of Medical Sciences in Poznan. The free and total form of cotinine and trans-3'-hydroxycotinine in urine were determined by the means of high performance liquid chromatography with spectrometry detection. The results of this studies indicated that in urine both cotinine and trans-3'-hydroxycotinine are conjugated with glucoronide acid in the high degree. The linear correlation between free and conjugated form of cotinine and whole cotinine concentration indicates the possibility of application of all three of them as biomarkers of tobacco smoke exposure. The high conjugation of trans-3'-hydroxycotinine with glucuronic acid (over 80 %), and high correlation between glucuronide and total trans-3'-hydroxycotinine concentration proves necessity of having the urine samples hydrolysed or determining the 3'-hydroxycotinine glucoronide, when application of 3-HC as a biomarker of tobacco smoke exposure is concerned. Our studies confirm other authors' observations that division of 3'-hydroxycotinine and cotinine concentrations might be used as a predictor of differences in cotinine metabolite ratio (polimorphism). The studies shown that using analytical equipment, nowadays available in the most laboratories (HPLC), it is possible to determined two biomarkers which are very useful and give various information, no matter whether they are conjugated with glucuronic acid, or not.