Nicotine Metabolite Ratio

**Semantic type:** Functional Concept

**Definition:** A biomarker of nicotine clearance that uses the ratio of two nicotine metabolites derived from smoking (3'-hydroxycotinine [3HC]/cotinine). This ratio reflects the activity CYP2A6 enzyme in the liver, and captures environmental influences on nicotine clearance as well.

**Synonyms:** - NMR