Nicotine & Metabolites

Diagnosis

Indications for Testing

  • Evaluate for recent use of nicotine-containing products
  • Document use of tobacco versus purified nicotine products (eg, assessing compliance with smoking cessation programs)
  • Verify that a person has abstained from nicotine-containing products (eg, qualifying patients for surgery)
  • Evaluate passive exposure to nicotine

Laboratory Testing

  • Nicotine and metabolites
    • Nicotine has a short half-life (24-84 minutes)
      • Nicotine levels are not always a good indicator of smoking status – better indicator is to measure metabolites
    • Metabolites of nicotine
      • Measure cotinine, trans-3’-hydroxycotinine (3-OH-cotinine), and nornicotine
      • Cotinine – major metabolite of nicotine
        • Half-life – approximately 16 hours
        • Metabolized to 3-OH-cotinine
      • Nornicotine – minor metabolite of nicotine
        • May be also be present in tobacco
  • Urine testing
    • Recommended over serum/plasma testing to detect chronic use
      • Analytes in urine are detectable over a longer period of time than in serum/plasma
    • 3-OH-cotinine metabolite may persist for weeks after cessation from long-term or heavy use of nicotine products
      • Cutoff of 100 ng/mL cotinine is frequently used for surgery qualification purposes
    • Anabasine – tobacco alkaloid also detected in urine
      • Not an expected result for individual using purified nicotine products
      • May distinguish active use of tobacco products from nicotine replacement therapy
  • Serum/plasma testing
    • Required when a valid urine specimen cannot be obtained (eg, anuretic or dialysis patient)
    • Detects recent use – typically within past 2 weeks
    • More closely correlated with oral fluid testing than urine

Pharmacogenetics and Therapeutic Drug Monitoring

  • Metabolism affected by genetic and non-genetic factors
  • Actual dose of nicotine depends on the nicotine source, route of administration, and frequency of use
    • ~90% of a dose eliminated in the urine
    • ~70-80% metabolized to cotinine
  • CYP2A6
    • Nicotine primarily metabolized by CYP2A6, UDP-glucuronosyltransferase and flavin-containing monooxygenase
      • Nicotine may affect pharmacokinetics of other drugs
    • Metabolic ratios of 3-OH-cotinine/cotinine can be used to evaluate CYP2A6 phenotype
      • Phenotype may be associated with altered nicotine metabolism
      • CYP2A6 is associated with dozens of genetic variants that are relatively common, such as *4 allele  
        • 17-24% – Japanese
        • 5-15% – Chinese
        • <5% – Caucasians and African Americans
      • Food (eg, grapefruit juice) or drugs may inhibit CYP2A6, thereby affecting nicotine metabolism

Clinical Background

Use of tobacco products, particularly smoking, is a leading but preventable cause of disease, disability, and death. Nicotine is also recognized as a risk factor for poor wound healing.

Epidemiology

  • Prevalence – 15-20% of adults are nicotine dependent
  • Sex – M>F

Pathophysiology

  • Principle source of exposure – tobacco products, purified nicotine products (eg, electronic cigarettes), or nicotine replacement therapy (eg, gum, patch, spray)
  • Found at low concentrations in potatoes, tomatoes,  eggplant, and sweet peppers
  • Absorbed through oral cavity, skin, urinary tract, and gastrointestinal tract
  • Increases heart rate, blood pressure, mobilization of blood sugars and catecholamines

Clinical Presentation

  • Cancers – lung, larynx, oral and nasal cavity, paranasal sinuses, esophagus, pancreas, liver, stomach, cervix, leukemia (AML, CML, CLL)
  • Cardiac and neurologic disease – leading cause of coronary disease, stroke
  • Pulmonary disease – chronic obstructive pulmonary disease (includes chronic bronchitis and emphysema), asthma, respiratory infections, overall decrease in pulmonary function
  • Pregnancy – difficulty in conceiving, intrauterine growth retardation, low birth weight
  • Second-hand smoke – a confirmed human carcinogen implicated in pulmonary disease, lung cancer and coronary artery disease in non-smokers

Indications for Laboratory Testing

  • Tests generally appear in the order most useful for common clinical situations
  • Click on number for test-specific information in the ARUP Laboratory Test Directory
Test Name and Number Recommended Use Limitations Follow Up
Nicotine and Metabolites, Urine, Quantitative 0092356
Method: Quantitative Liquid Chromatography-Tandem Mass Spectrometry

Assess active exposure to nicotine and compliance with smoking-cessation programs

Use to confirm cotinine screening results

Detects nicotine, cotinine (metabolite), 3-OH-cotinine (metabolite), nornicotine (metabolite), and anabasine (tobacco biomarker) in urine

A cutoff of 100 ng/mL cotinine is frequently used for surgery qualification purposes

Analytical sensitivity – 100 ng/mL

May not differentiate between passive and active nicotine exposure

Will not differentiate nicotine exposure from nicotine replacement therapy and tobacco use

Assay may crossreact with other nicotine metabolites

Failure to detect anabasine is not definitive evidence of tobacco abstinence

 
Nicotine and Metabolites, Serum or Plasma, Quantitative 0092361
Method: Quantitative Liquid Chromatography-Tandem Mass Spectrometry

Assess active exposure to nicotine

Confirmation of cotinine screen results

Detect and monitor nicotine, cotinine (metabolite), and 3-OH-cotinine (metabolite) in serum or plasma

Best test to document nicotine cessation over time

Order when valid urine specimen cannot be obtained (eg, anuretic or dialysis patient)

A cutoff of 10 ng/mL cotinine is frequently used for surgery qualification purposes

Analytical sensitivity – 100 ng/mL

May not differentiate between passive and active nicotine exposure

Does not detect anabasine

Will not differentiate nicotine exposure from nicotine replacement therapy and tobacco use

Assay may crossreact with other nicotine metabolites

 
Cotinine Screen, Urine 2007081
Method: Enzyme Multiplied Immunoassay Technique

Assess active exposure to nicotine and compliance with smoking-cessation programs

Qualitative screen recommended for use in documenting abstinence from nicotine-containing products, such as in surgery qualifications

Positive result reported at 100 ng/mL

Confirm unexpected results by LC-MS/MS

Analytical sensitivity – 100 ng/mL

Assay may cross-react with other nicotine metabolites

May not differentiate between passive and active nicotine exposure

Will not differentiate nicotine exposure from nicotine replacement therapy and tobacco use