From the Research
Smoking does affect hemoglobin levels in the blood, causing an increase in hemoglobin levels due to the body's compensation for reduced oxygen-carrying capacity. This is because carbon monoxide (CO) from cigarette smoke binds to hemoglobin, forming carboxyhemoglobin, which reduces the oxygen-carrying capacity of blood [ 1 ]. As a result, the body produces more red blood cells, a condition called secondary polycythemia, to maintain adequate oxygen delivery to tissues.
Key Findings
- Smokers typically have higher hemoglobin levels than non-smokers, with an increase of approximately 0.3-0.5 g/dL in women and 0.5-0.7 g/dL in men [ 2 ].
- The elevation in hemoglobin levels is the body's attempt to compensate for impaired oxygen delivery, not an indication of better oxygen transport [ 1 ].
- Quitting smoking can normalize hemoglobin levels within 2-3 months as carbon monoxide levels decrease and normal oxygen transport resumes.
Clinical Implications
- Smoking can mask anemia, reducing the utility of hemoglobin level to detect anemia [ 2 ].
- Minimum hemoglobin cutoff values should be adjusted for smokers to compensate for the masking effect of smoking on the detection of anemia [ 2 ].
- Secondary polycythemia, associated with smoking, may have a protective effect on severe COPD exacerbations [ 3 ].
Recommendations
- Smokers should be aware of the potential increase in hemoglobin levels and the associated risks and benefits.
- Clinicians should consider the effects of smoking on hemoglobin levels when interpreting laboratory results and diagnosing anemia.
- Further research is needed to explore the potentially protective role of increased hemoglobin in smokers with COPD [ 3 ].