Which of the following is NOT a biomarker for smoking detection?

Nicotine itself is not considered a reliable biomarker for smoking detection due to its rapid metabolism and variability in clearance among individuals. After a person smokes, nicotine levels in the blood peak quickly and then decline substantially within hours, making it difficult to determine recent smoking behavior based solely on nicotine concentration.

In contrast, other options are established biomarkers that can indicate recent smoking. Serum cotinine, a metabolite of nicotine, remains in the body longer and provides a more stable measurement of tobacco exposure. Carboxyhemoglobin is a product of carbon monoxide binding to hemoglobin, which reflects exposure to smoke and is particularly relevant for assessing the impact of smoking on oxygen transport. Thiocyanate levels can also increase as a result of smoking, making it another marker of tobacco use.

Understanding these distinctions is vital for accurate assessment and diagnosis in clinical practice, particularly in addiction medicine and smoking cessation efforts.