cotinine image from New Medical Terms



Definition An alkaloid of tobacco that is detectable for up to a week after a person smokes the last cigarette, and used as a biomarker for exposure to tobacco smoke.

Metabolism Like nicotine, cotinine (CTN) is metabolised by CYPA26

CTN levels

< 10 ng/mL         Non-smoker

11–30 ng/mL      Light smoker or passive exposure

> 300 ng/mL       Heavy active smoking

Body fluids measured Urine, serum, saliva.

Comment Urine CTN concentrations are 4- to 6-fold higher than in other body fluids. It is measured by insurers to determine whether subjects applying for health and/or life insurance are indeed non-smokers and entitled to lower premium costs, as non-smokers are usually healthier. CTN levels are higher for longer in those who smoke menthol, given that menthol can compete with enzymatic metabolism of CTN.


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