The RBC level is increased in hemolytic states such as the thalassemias, spherocytosis, hemoglobin SS, and acquired hemolytic anemias. It is decreased in paroxysmal nocturnal hemoglobinuria and in relapse of megaloblastic anemia. Potent inhibitors of cholinesterase may present important clinical toxicological problems. Both RBC acetylcholinesterase and plasma cholinesterase are usually inhibited. The effect on the plasma enzyme is more marked, however, and serum levels are usually utilized in diagnosis and assessment of recovery.
Recovery is best determined by looking for a plateau in erythrocyte cholinesterase activity.
If there is suspicion that a decrease in cholinesterase activity may not relate to the inhibitor effect of an organophosphate then red cell level of acetylcholinesterase should be obtained. If both serum and RBC levels are significantly decreased, findings are those of exogenous toxic effect.