Use of Urinary Thiocyanate as a Biomarker of Tobacco Smoke

Data from National Health and Nutrition Examination Survey for the years 2005-2010 were used to develop cut off levels for urinary thiocyanate (USCN) to distinguish smokers from nonsmokers aged ≥ 20 years. A cut off of (i) 1840 ng/ml for USCN was able to distinguish smokers from nonsmokers with a sensitivity of 80.7% and a specificity of 80.8%, (ii) 2630 ng/ml for USCN was able to distinguish smokers from nonsmokers with exposure to SHS at home with a sensitivity of 82.0% and a specificity of 82.1%, and (iii) 1550 ng/ml for USCN was able to distinguish smokers from nonsmokers without exposure to SHS at home with a sensitivity of 75.7% and a specificity of 75.6%. Adequacy of these cut offs was evaluated by applying them to NHANES data for 2011-2012. Sensitivities and specificities for 2005-2010 and 2011-2012 data were comparable. USCN levels for smokers were 4.6 times of what they were for nonsmokers (4102.6 vs. 890.6 ng/ml, p<0.01). Those aged 20-64 years had higher levels of USCN than those aged 65+ years (1390.0 vs. 855.9 ng/ml). Males had higher levels of USCN than females (p<0.01). NonHispanic whites had statistically significantly higher levels of USCN than non-Hispanic blacks (p<0.01).