Smokingis the most commoncause of secondary polycythemia and mayinduce leukocytosis.We studied the relationship between hematopoietic growth factors and erythrocytosis and leukocytosis. Two sets of healthy male volunteers, consisting of 177 and 202 (age: 19-59 years) were each divided into four groups according to whether or not they smokedat least one package daily and their leukocyte count. Serum erythropoietin (Epo) concentration and granulocyte-colony stimulating factor (G-CSF) concentration were measured in the 177 and 202 volunteers, respectively. The meanserum Epoconcentration was lower in smokers than in nonsmokers(p=0.01 in the subjects without leukocytosis and p=0.107 in those with leukocytosis, respectively). After 3 smokers stopped smoking, the Epo concentration increased 2 weeks later, and remained constant for 20 weeks. Smokers tended to have a higher meanserum G-CSFconcentration than nonsmokers in the subjects without leukocytosis. Neither Epo nor G-CSFis the main etiology of smokers' polycythemia, and Epo production may be down-regulated by an elevated red-cell volume. (Internal Medicine 36: 680-684, 1997)

SummaryA primary prevention study based on the double blind method was conducted to clarify both the improvement of serum lipid levels and the prevention of the arteriosclerotic diseases through the

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