Influence of fibrinogen and haematocrit on erythrocyte sedimentation kinetics

This study investigates the influence of haematocrit, fibrinogen concentrat ion and fibrinogen availability (amount of fibrinogen per red blood cell) o n erythrocyte sedimentation. The Westergren technique was applied to blood samples from 36 subjects and to their blood manipulated to haematocrits of 10, 20, 30 and 40%. Readings were taken every 10 minutes for 300 minutes. P revious studies indicate that erythrocyte sedimentation occurs in three pha ses. In this study, we show that haematocrit has little influence on either the rate of fall of particles in the first phase (m(1)) or the duration of the first phase. This is also true for fibrinogen availability and for fib rinogen concentration at low haematocrits. At high haematocrits mi increase s with fibrinogen concentration. The rate of fall of rouleaux during phase 2 (m(2)) and ESR60, both decrease exponentially with haematocrit and increa se linearly with fibrinogen concentration. While m(2) is more closely corre lated to fibrinogen availability than to fibrinogen concentration or to hae matocrit, this is not the case for ESR60. Thus haematocrit, fibrinogen conc entration and fibrinogen availability are more important to the velocity of sedimentation in the second phase than to the sedimenting velocity during phase 1 or to the duration of phase 1.