Objective: Smoking has been reported to be one of the risk factors of myelodysplastic syndrome (MDS). In order to clarify the process of progression to MDS in a certain group of smokers, it is important to identify the initial hematological abnormalities associated with the early stage of MDS in smokers.
Methods: Relationships of hematological parameters such as WBC count, RBC count, Hb, Ht, MCH and MCV with level of smoking were investigated by univariate and multivariate analyses in 234 male workers at a single workplace after obtaining informed consent.
Results: Univariate analysis demonstrated that correlations of smoking-related factors (number of cigarettes per day, duration of smoking [years] and smoking index [defined as number of cigarettes per day x duration of smoking]) with WBC count, Ht, MCH and MCV were significantly positive. Multivariate analysis using age, smoking-related factors, alcohol intake and BMI as explanatory valuables showed that age, alcohol intake and BMI were not confounding variables for smoking-related factors and revealed a remarkable significant positive correlation between each smoking-related factor and MCV.
Conclusion: Smoking-associated macrocytosis, which was demonstrated in the present study, was not due to deficiency of vitamin B₁₂ or folic acid because of no pancytopenia observed but was considered to be a qualitative abnormality of erythrocytes. Taken together with the findings of previous studies concerning smoking-associated functional abnormalities of erythrocytes and leukocytes and the high incidence of MDS in smokers, our results indicate that idiopathic macrocytosis in smokers could be an initial sign of progression to MDS, in which macrocytosis and multi-lineage abnormalities are characteristic findings.