Elevation of blood viscosity, aggregation of red cells, haematocrit values and fibrinogen levels with cigarette smokers.

A study of blood viscosity factors was carried out on male smokers and non-smokers (125 volunteers) in the age group 45 to 55 years. The smoker's group exhibited elevated haematocrit values, fibrinogen levels and blood viscosity (P less than 0-025), and increased aggregation of red cells and plasma viscosity (P less than 0-005). Especially in the dependence of aggregation of red cells on the level of fibrinogen, the smokers of blood group O showed higher values than smokers of blood group A (P less than 0-01). Elevation of blood viscosity factors and functions in smokers suggests that pathways to ischaemia and thrombosis, to which smokers are more prone than non-smokers, may move through the blood high-viscosity syndromes.