Pulmonary functional parameters and blood cotinine level in chronic obstructive pulmonary disease.

Introduction: Smoking is the leading cause of chronic obstructive pulmonary disease (COPD) and cotinine is reliable marker of tobacco exposure. We aimed to investigate the relationship between pulmonary function tests (FVC%, FEV1, FEV1/FVC and FEF25-75%), smoking history and blood cotinine levels in healthy volunteers as a control and patients who have COPD in our study.

Materials And Methods: One hundred and two COPD patients and 106 healthy volunteers who admitted to our institution were included. Spirometric investigations of the patients and volunteers were performed. A simple, rapid and reliable gas chromatography-mass spectrometry (GC-MS) method was used for determination of cotinine levels in blood samples.

Result: The cut-off value of cotinine was determined as 41.12 ng/mL (97.2% sensitivity and 100% specificity). A significant relationship was observed between average pack-year and cotinine level in current smoker group (p< 0.05). The mean cotinine levels were 6.1, 8.8, and 467.0 ng mL-1 in never smokers, ex-smokers and current smokers, respectively. No relationship was observed between cotinine level and FVC%, FEV1% and FEV1/FVC (p> 0.05). In patient group, there was also no relationship between FEF25-75% and cotinine level however, in control group-smokers a negative correlation was found (p< 0.05; r= -0.372).

Conclusions: We observed once again with our study that cotinine is a reliable marker of tobacco exposure. The most obvious result is the negative correlation between FEF25-75% value and cotinine level and this result may be caused by the effect of smoking in the peripheral airways at early stages of COPD.