[Age and whole blood viscoelasticity. A risk factor study].

To assess whether the viscoelastic properties of whole blood might be influenced by age, we measured viscoelasticity of whole blood (VEWB) and plasma at different shear rates in 84 healthy adult subjects. Additionally, we examined the relations between VEWB and gender, cigarette smoking, and oral contraceptive use. VEWB (shear rates 10/s and 50/s, adjusted to a haematocrit of 45%), viscosity of plasma (shear rate 10/s), aggregation index, shear resistance and flexibility index of erythrocytes were measured with an oscillating capillary rheometer and densitymeter. By means of univariate analysis, age was found to increase whole blood elasticity at low shear rates and shear resistance of erythrocytes. Concerning high shear rates, this relationship could only be established in males. The rheologic values of women who had taken oral contraceptives for at least one year were not related to age. Multiple regression analysis demonstrated that whole blood elasticity at low shear rates and shear resistance of erythrocytes were significantly related to age and the intake of oral contraceptives. On the contrary, there was no relationship between age and whole blood and plasma viscosity as well as aggregation and flexibility indices.