Hilary Tindle, MD, MPH, associate professor of medicine, Vanderbilt University, discusses the nicotine metabolite ratio (NMR) is and how it's used to help identify vulnerable individuals for lung cancer and heart disease.
The nicotine metabolite ratio (NMR) is a genetically informed biomarker that shows how nicotine is broken down by the body and varies across individuals, says Hilary Tindle, MD, MPH, associate profesor of medicine, Vanderbilt University.
What is the NMR and how does faster metabolism contribute to a “high-risk” endophenotype?
The nicotine metabolite ratio is a genetically informed biomarker. And all it is, is the ratio or fraction of 2 breakdown products of nicotine. Nicotine in a cigarette is broken down by the liver, and nicotine has a very short half-life of only about 2 hours. But that varies a lot according to a person's genetic makeup. People who tend to break down nicotine faster are heavier smokers, they tend to smoke more, they have more difficulty quitting; therefore, they smoke for more years of their life. And therefore, they are at higher risk of smoking-related diseases, such as lung cancer and heart disease.
The nicotine metabolite ratio can be measured in blood, saliva, or even urine by a doctor. It's used in the hospital, for example, before a surgery to verify if an individual is continuing to smoke or has successfully quit smoking—but this ratio is very important for quitting. So again, people who have a higher nicotine metabolite ratio, 0.31 or higher is a commonly used cut off, those folks probably have a harder time quitting and they may even need different medication.