Tobacco smoking causes secondary polycythemia and a mild leukocytosis among heavy smokers in Taif City in Saudi Arabia.

Tobacco smoking is a common risk factor of cardiovascular diseases, cancers and heart health problems. In Taif, the number of secondary polycythemia patients is increasing dramatically and most of those patients are heavy smokers. Therefore, this study is an attempt to understand the pathophysiological mechanism behind that problem. Whole blood and serum samples were collected from forty healthy people and forty tobacco smokers, voluntary for this study. Complete blood counts revealed a significant increase in the red blood cell count, hemoglobin concentrations, hematocrit and neutrophils with some elevations in total white blood cells, lymphocytes and monocytes. Moreover, serum analysis of both erythropoietin and interleukin-7 showed a significant reduction in their levels among smokers which were about 35% and 65% respectively. Gene expression study showed a significant upregulation of RAG-1, RAG-2 and EPOR-1 genes caused by tobacco smoking. In conclusion, data presented in the current study suggest that tobacco smoking might cause alveolar tissue inflammation and vascular injury causing an immune response that elevates the white blood cells count. Another suggestion is that tobacco smoking defects the pulmonary gaseous exchange mechanism leading to the secondary polycythemia indicated by the increase in red blood cell count, hemoglobin levels, hematocrit and by the low serum erythropoietin levels.