Cotinine

Cotinine is a major metabolite of nicotine. Exposure to nicotine can be measured by analyzing cotinine levels in the blood, saliva, or urine. Nicotine is highly specific for tobacco smoke, so serum cotinine levels track exposure to tobacco smoke and its toxic constituents.

These tests might be useful in determining level of exposure to environmental tobacco smoke (ETS) in children with frequent asthma exacerbations severe enough to warrant emergency room visits and/or hospital admissions. In these cases, cotinine levels may provide proof of significant ETS exposure and demonstrate medical neglect. One study (Mannino, et al., CHEST 2002) found that asthmatic children with high levels of smoke exposure (compared to those with low levels) were more likely to have moderate or severe asthma.

Cotinine levels
0.050 ng/mL	limit of detection
0.050 – 0.115 ng/mL	low level
0.116 – 0.639 ng/mL	intermediate level
0.640 – 20 ng/mL	high level

To find out more about exposure to environmental tobacco smoke and cotinine levels, read the Centers for Disease Control and Prevention’s Cotinine Fact Sheet.