nicotine and metabolites (Nicotine, Cotinine, 3-Hydroxy Cotinine, Nornicotine, Anabasine)
المؤلف:
Kathleen Deska Pagana, Timothy J. Pagana, Theresa Noel Pagana.
المصدر:
Mosbys diagnostic and laboratory test reference
الجزء والصفحة:
15th edition , p649-651
2025-07-22
332
Type of test Urine/blood
Normal findings
Test explanation and related physiology
Nicotine is metabolized into cotinine and 3-hydroxy cotinine, which are measurable in urine and serum. The word “cotinine” is actually an anagram of “nicotine”—the eight letters are rearranged. In addition to nicotine and metabolites, tobacco products also contain other alkaloids (anabasine and nornicotine). These tests are used to assess compliance with smoking cessation programs and to qualify for surgical procedures. They are also used by insurance companies to determine whether the applicant is a smoker.
Cotinine and 3-hydroxy cotinine have in vivo half-lives of approximately 20 hours and are typically detectable for several days to up to 1 week after the use of tobacco. Because the level of these metabolites in the blood is proportionate to the amount of exposure to tobacco smoke, it is a valuable indicator of tobacco smoke exposure. Nicotine and its metabolites can be measured in the serum, urine, and other biofluids (most commonly the saliva). Cotinine is found in urine from 2 to 4 days after tobacco use. Serum or plasma testing is required when a valid urine specimen cannot be obtained or to detect recent use (within past 2 weeks). Blood cotinine will increase no matter how the tobacco is used (smoked, chew, dip, or snuff products). Nicotine levels have an in vivo half-life of approximately 2 hours, which is too short to be useful as a marker of smoking status.
Anabasine (only measured in the urine) is present in tobacco products but not nicotine replacement therapies. Nicotine, cotinine, 3-hydroxy cotinine, and nornicotine are also elevated by the use of any of the nicotine replacement gum, patch, or pill products. The presence of anabasine greater than 10 ng/mL or nornicotine greater than 30 ng/mL in urine indicates current tobacco use, irrespective of whether the subject is on nicotine replacement therapy. The presence of nornicotine without anabasine is consistent with use of nicotine replacement products. Heavy tobacco users who abstain from tobacco for 2 weeks exhibit urine nicotine values less than 30 ng/mL, cotinine values less than 50 ng/mL, anabasine values less than 2 ng/mL, and nornicotine values less than 2 ng/mL. Passive exposure to tobacco smoke can cause accumulation of nicotine metabolites in nontobacco users. Urine cotinine has been observed to accumulate up to 20 ng/mL from passive exposure. Neither anabasine nor nornicotine accumulates from passive exposure. Because hydration status and renal function may affect urinary cotinine results, a spot urine cotinine test is accompanied by a spot urine creatinine.
For smokers, another method of determining tobacco use is expired carbon monoxide testing. Again, a relatively short half-life (~4 hours) limits the reliability and accuracy. Furthermore, carbon monoxide testing is unable to detect the use of smokeless tobacco.
Interfering factors
• Menthol cigarettes may increase cotinine levels because the menthol retains cotinine in the blood for a longer period of time.
• Diluted or adulterated urine may alter results.
Procedure and patient care
Before
* Explain the procedure to the patient and indicate the type of specimen needed.
• Obtain an accurate history of recent tobacco use.
During
Blood
• Collect venous blood in a red-top, lavender-top (EDTA), or pink-top (K2 EDTA) tube. See inside front cover for Routine Blood Testing.
Urine
• Obtain a random spot urine specimen of at least 5 mL. See inside front cover for Routine Urine Testing.
• Immediately transport the specimen to the laboratory.
Saliva
• Ask the patient to spit at least 1 mL of saliva into a spit container.
• Alternatively, dental gauze rolls can be placed in the mouth for 15 minutes and then placed in a storage container for transport.
After
• Keep the specimens in a cool place if they cannot be trans ported to the laboratory immediately.
Abnormal finding
Tobacco exposure
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