Alterations in haematological and coagulation parameters among smokers: A case–control study in Enugu Metropolis, Nigeria

Smoking is a major public health concern associated with systemic inflammation, cardiovascular complications, and hematological alterations. This study assessed differences in haematological and coagulation parameters between smokers and non-smokers in Enugu Metropolis, Nigeria. A case–control design was employed, involving 44 smokers and 44 non-smokers aged 18–50 years. Full blood count indices and coagulation parameters were analyzed using automated analyzers and standard laboratory methods. Smokers demonstrated significantly higher median white blood cell counts (6.0 ×10⁹/L vs. 4.0 ×10⁹/L, p < 0.001), with elevated lymphocyte (2.9 ×10⁹/L vs. 2.1 ×10⁹/L, p < 0.001) and MID cell counts (1.0 ×10⁹/L vs. 0.3 ×10⁹/L, p < 0.001). Among red cell indices, smokers had higher median haemoglobin levels (13.4 g/dL vs. 13.2 g/dL, p = 0.02), mean corpuscular haemoglobin (28.0 pg vs. 27.2 pg, p = 0.01), and mean corpuscular haemoglobin concentration (32.4 g/L vs. 31.5 g/L, p = 0.03). Platelet counts (198 ×10⁹/L vs. 178 ×10⁹/L, p = 0.004) and plateletcrit (1.8% vs. 1.6%, p = 0.03) were also significantly higher among smokers. Coagulation analysis revealed prolonged prothrombin time (17.6 sec vs. 14.8 sec, p = 0.001), thrombin time (21.4 sec vs. 19.0 sec, p = 0.02), and international normalized ratio (1.5 vs. 1.1, p = 0.001) in smokers, while activated partial thromboplastin time and fibrinogen levels showed no significant differences (p > 0.05). These findings indicate that smoking is associated with significant alterations in haematological and coagulation parameters, suggesting a disruption in haemostatic balance. These changes may have implications for clinical risk stratification and monitoring.