The effect of cigarette smoking on hemoglobin levels and anemia screening.

The relationships among cigarette smoking, hemoglobin concentration, and carboxyhemoglobin concentration were examined using data from the Second National Health and Nutrition Examination Survey. Among women, smokers had a mean (+/- SE) hemoglobin level of 137 +/- 0.4 g/L, significantly higher than the mean hemoglobin level of 133 +/- 0.5 g/L for never-smokers. Among men, the mean hemoglobin levels for smokers and never-smokers were 156 +/- 0.4 and 152 +/- 0.5 g/L, respectively. No significant difference in mean hemoglobin was noted between ex-smokers and never-smokers. Mean hemoglobin levels and carboxyhemoglobin levels increased progressively with the number of cigarettes consumed per day. Cigarette smoking seems to cause a generalized upward shift of the hemoglobin distribution curve, which reduces the utility of hemoglobin level to detect anemia. Among women of comparable socioeconomic status, the prevalence of anemia was 4.8% +/- 0.6% among smokers, compared with 8.5% +/- 1.2% among never-smokers. This study suggests that minimum hemoglobin cutoff values should be adjusted for smokers to compensate for the masking effect of smoking on the detection of anemia.