Anaemia and cigarette smoking

TL;DR

This narrative review evaluates literature on how cigarette smoking affects anaemia, noting that smoking often raises haemoglobin and can mask anaemia while also influencing iron, folate, haemolytic, and aplastic anaemia pathways. It concludes that effects vary by anaemia type and that further studies are needed.

Key findings

• Smoking-associated Hb elevation may mask anaemia: among women of comparable socio-economic status, anaemia prevalence was 4.8% in smokers vs 8.5% in never-smokers (Nordenberg et al., 1990). Hb increases are generally reversible; healthy ex-smokers show no Hb difference vs nonsmokers, though long-term smokers with COLD or emphysema may have persistently elevated Hb/polycythaemia.
• Folate levels in serum or RBCs are reduced in smokers, in both nonpregnant and pregnant individuals, and the risk of reduced RBC folate relates to cigarettes smoked per day; vitamin B12 findings remain inconsistent. Smoking is well documented as correlated with myeloid leukaemia, with relative risk correlated with quantity smoked; benzene is linked to aplastic anaemia, but AA-smoking data are rare (Linet et al., 1989 found no significant correlation in 59 patients), and average smoker benzene uptake of approximately 1.8 mg/day may be too low to show AA effects.
• In sickle cell disease, smoking-related reduced oxygenation may precipitate crisis, acute chest syndrome is more frequent in smokers, and children exposed to environmental tobacco smoke had more inpatient sickle cell crises (West et al., 2003). HbCO is elevated in smokers but no correlation with vaso-occlusive severity was detected (Sears et al., 2001); CO may stabilize Hb Zurich and reduce haemolysis.
• In pregnancy, most studies show no significant Hb difference between smoking and nonsmoking women, but fetuses of mothers who continued smoking had elevated HbF and higher haematocrit levels.

Methods

• Narrative review/evaluation of the current literature on the impact of cigarette smoking on various forms of anaemia; no primary data are collected.
• The text does not describe a systematic search strategy, inclusion criteria, or quantitative meta-analysis; it synthesizes cited studies across iron homeostasis, haemolytic anaemia, megaloblastic anaemias, and aplastic anaemia/haematotoxicity.

Limitations

• Stated: human data on cigarette smoke-induced haemolysis are inconclusive; specific data on thalassaemia and cigarette smoking are not available; AA-smoking data are rare; it is unclear whether reduced folate correlates with higher megaloblastic anaemia incidence; vitamin B12 data are inconsistent; further studies are needed.
• Evident: as a narrative review, it relies on previously published studies and does not report a systematic search or formal quality assessment; conclusions may be constrained by heterogeneity and small study sizes noted in the text.