Length of sedimentation reaction in undiluted blood (erythrocyte sedimentation rate): variations with sex and age and reference limits.

Although the length of sedimentation reaction in blood (LSRB) (commonly, but improperly called erythrocyte sedimentation rate, ESR) has long been used in clinical laboratories because it is simple and low-cost, its sensitivity and specificity are unsatisfactory. Usually, the values are reported using the Westergren method with sodium citrate-anticoagulated specimens. We used a new procedure, the TEST1, which measures the length of sedimentation reaction in undiluted K3EDTA anticoagulated blood samples following ICSH (International Committee for Standardization in Haematology) recommendations. Samples obtained from 840 reference individuals (430 females and 410 males, mean age 44 and 46.5 years respectively, range 1 to 90 years) were utilised to estimate the reference limits. The subjects, classified by sex, were subdivided into four statistically different age groups to determine the reference limits (2.5th and 97.5th percentiles). Sex difference was statistically significant in two age groups, from 14 to 50 (p < 0.0001) and from 50 to 70 years (p < 0.01). We did not observe significant sex difference within the age bracket from 1 to 14 years and from 70 to 90 years. In both sexes LSRB values increased with age, in significant correlation with fibrinogen concentration (p < 0.0001), and became significantly higher in subjects older than 70 compared to all the younger subjects (p<0.01 in females and p < 0.02 in males). Thus, we defined adequate reference ranges in elderly.