Plasma, serum and whole-blood viscosity variations with age, sex, and smoking habits.

To study the influence of age, sex, and smoking habits on rheology, the authors measured plasma (PV), serum (SV), native (NBV), and corrected (CBV) blood viscosity with a computerized rotational viscometer in 152 blood donors (86 men and 66 women) and in 20 healthy persons (4 men and 16 women) attending smoke aversion treatment. None of the viscosity measures or erythrocyte sedimentation rate changed significantly with age, whereas hematocrit (HC) and fibrinogen concentration (FC) both increased with ageing (p < 0.05 and p < 0.001, respectively). Higher (p < 0.001) values of NBV and HC were found in men than in women, whereas higher values were found in women than in men for FC (p < 0.01) and ESR (p < 0.001). In blood donors, moderate smoking (mean twelve cigarettes/day) significantly influenced only ESR, which was higher (p < 0.001) in smokers than in nonsmokers. In heavy smokers (mean twenty-one cigarettes/day), however, higher (p < 0.001) PV, SV, and NBV were found, as well as higher (p < 0.01) FC and HC as compared with nonsmoking blood donors.