Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (1087 page)

NICOTINE/COTININE
*

   Definition

   Nicotine is a hygroscopic alkaloid obtained from tobacco. Cotinine is the major metabolite of nicotine.

   
Normal range
(serum): Cotinine

   Nonsmokers: <6 ng/mL

   Cigarette smokers: 10–50 ng/mL

   Use

   Insecticide and fumigant

   Constituent of tobacco products

   Constituent of smoking cessation products

   Interpretation

   Serum cotinine concentrations may be up to 10 times greater than corresponding nicotine level in smokers.

   Urine nicotine and cotinine concentrations in smokers are typically >1,000 ng/mL.

   Limitations

   Screening tests are immunoassay based typically target cotinine with a cutoff concentration of 100–500 ng/mL (for urine). Test may cross-react with 3-hydroxy cotinine.