Intraindividual stability of human erythrocyte cholinesterase activity

Clin Chem. 2007 Jul;53(7):1358-63. doi: 10.1373/clinchem.2006.085258. Epub 2007 May 10.

Abstract

Background: Erythrocyte cholinesterase (RBC-ChE) activities serve as useful and sensitive biomarkers to monitor exposure to cholinesterase-inhibiting substances, such as chemical warfare nerve agents and pesticides. Although the interindividual variation of RBC-ChE is well characterized, the magnitude of intraindividual variation for RBC-ChE remains controversial. An accurate measure of intraindividual variation is critical for establishing the appropriate frequency of RBC-ChE testing.

Methods: We retrospectively tracked the intraindividual variation of RBC-ChE activities among 46 male nerve agent workers from a single US Army depot that participated in a medical surveillance program requiring periodic RBC-ChE monitoring. All RBC-ChE analysis was performed by the same medical laboratory technician by the delta pH method.

Results: A mean of 38 and a median of 37 RBC-ChE measurements were available for each worker. The mean duration of employment for these workers was 20 years (median, 21 years). The mean CV for RBC-ChE in this set of 46 workers was 3.9%. Linear regression analysis of the data for each worker resulted in a mean slope of 0.0010 delta pH units/h per year.

Conclusions: RBC-ChE activities increased in each person by a mean of 0.01 delta pH units/h every 10 years, which is a negligible rate. These findings highlight the stability of RBC-ChE activities over time in a given individual and may have important policy implications regarding the appropriate frequency of RBC-ChE testing.

Publication types

  • Comparative Study

MeSH terms

  • Biomarkers / blood
  • Chemical Industry
  • Cholinesterase Inhibitors / adverse effects
  • Cholinesterases / blood*
  • Erythrocytes / enzymology*
  • Humans
  • Linear Models
  • Male
  • Occupational Exposure / adverse effects
  • Organophosphorus Compounds / adverse effects
  • Reference Values
  • Retrospective Studies
  • Time Factors

Substances

  • Biomarkers
  • Cholinesterase Inhibitors
  • Organophosphorus Compounds
  • Cholinesterases