Inverse relationship between serum cholinesterase activity and the administration of cyclophosphamide: an Index of cyclophosphamide therapy

To determine whether serum cholinesterase activity can be amonitoring index of cyclophosphamide therapy in patients withsteroid-resistant glomerulopathy, we compared the cholinesteraseactivity of 37 patients who received a combined therapy thatincluded the use of cyclophosphamide, prednisolone, antiplateletdrugs, and anticoagulant drugs, with the cholinesterase activityof 25 patients who received prednisolone therapy that excludedcyclophosphamide from the combined therapy. In the prednisoloneand the combined groups, cholinesterase activity declined asshown in the following formula: Y=371–26.4xlog(X): (r²=0.28),Y=444–147.7xlog(X): (r²=0.95), respectively. (Y: cholinesteraseactivity, X: the day after treatment). In the combined therapygroup, the prevalence of adverse reactions following treatmentin the subgroup below 200 U/I of cholinesterase activity wassignificantly greater (P<0.01) than that in the subgroupabove 200 U/I of cholinesterase activity. However, there wasno significant difference (P<0.25) in the prevalence of adversereactions between the subgroups with more or less than 184 U/Iof cholinesterase activity following treatment. These resultssuggest the importance of not going below 200 U/I of cholinesteraseactivity after treatment when the normal cholinesterase activityrange is between 300 and 760 U/I (e.g. less than 65% of thelowest value of the normal range of other hospitals) in orderto eliminate the hazards of cyclophosphamide to the patientswith steroid-resistant glomerulopathy.