(kōt'ĭn-ēn‵ )

An alkaloid that is the principal metabolite of ingested or inhaled nicotine. It can be detected in saliva, serum, and urine. It is used as a biomarker that indicates recent tobacco use. People who do not smoke or chew tobacco products, and who are not exposed to secondhand smoke typically have serum cotinine levels less than 10 ng/mL.

SEE: tobacco.