A physical theory of erythrocyte sedimentation.

A new physical theory of erythrocyte sedimentation is proposed. Various assumptions underlying Stokes' formula are first criticized. An explicit formula is proposed, taking into account some of the results of recent experimental investigations including the effect of upward flow of plasma and the time course of growth of aggregates. It is generally shown that the sedimentation curve without aggregation never becomes a sigmoid. Our formula is applicable to the increased ESR due to the aggregation of erythrocytes. The sedimentation velocity depends not only on the hematocrit and the ultimate size of the aggregates, but also on the retardation time of the growth of aggregates in conformity with the experimental result of Kernick et al.