Background:
Smoking is the most incriminated and studied risk factor for COPD, but other factors like air pollution are also linked to this disease. Assessment of nicotine dependence may be performed clinically or paraclinical.

Objective:
To assess useful biological markers in COPD smoking patients.

Methods:
In this observational study, 52 patients diagnosed with different stages of COPD were included and clinical features and biological variables were statistically assessed. The biological markers measured were ALAT-alanine amino aminotransferase, ASAT - aspartate aminotransferase, urea, creatinine, total cholesterol, triglycerides, high density lipoprotein cholesterol (HDL-CHOL), low density lipoproteins-cholesterol (LDL-CHOL), lactate dehydrogenase (LDH), and uric acid.

Results:
Significant correlations were obtained between COPD stages and serum uric acid concentrations (r=0.4; p<0.05), smoking status (smoker/non-smoker/ex-smoker) and total serum cholesterol values (r=0.45; p<0.05), but also between serum urea concentrations and the number of pack-years for the smoker/ex-smoker groups (r=0.45; p<0.05). The statistical difference between the investigated smoker/non-smoker/exsmoker groups was assessed with the Man-Whitney U test. Thus, the statistical results showed a statistically significant difference between the smoker/ex-smoker groups given by the following biological variables: total cholesterol (p=0.012), LDL-CHOL (p=0.039), PY-pack-years (p=0.006). The results from the descriptive statistics point to LDL-CHOL values for smokers and ex-smokers of 106.34 mg/dL and 110.53 mg/dL, respectively, slightly higher than the reference biological range compared to the mean LDL-CHOL concentration values in nonsmokers (98.28 mg/dL).

Conclusions:
The results show that lipid metabolism seems to be affected by smoking and other studies conducted in this field also show a correlation between this habit and high levels of triglycerides and low levels of HDL cholesterol. Uric acid can be used as a biomarker of exposure to tobacco smoke.