Dose-effect relationship between smoking and blood rheology.

Five groups of male blood donors were investigated. The first group had never smoked, the second were ex-smokers, the third smoked between 10 and 20 cigarettes per day, the fourth between 21 and 40, and the fifth more than that. Haematocrit, white cell count, plasma and native blood viscosity, blood cell filterability and aggregation, plasma colloid oncotic pressure as well as fibrinogen were measured. Results show that smoking is associated with a progressive significant deterioration of the above haemorheologic variables. These changes are interpreted as an absolute and a relative polycythaemia possibly in conjunction with a chronic inflammatory process. It is concluded that smoking induces a dose-related increase in viscosity of blood among young men which is reversible by abstention.